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A Critical Period For Lactation Fetishes

Enquist et al on lactation fetishes is one of my favorite papers.

They wonder – as we’ve all wondered at one point or another – how people develop fetishes. One plausible hypothesis is “sexual imprinting”. During childhood, you have a critical period (maybe ages 1 to 5) where you figure out what sex is. If you see some weird stuff during that time, you could end up with a fetish. For example, a child who sees latex used in a sexualized way (for example, they catch a glimpse of a sexy movie where someone is wearing latex) might grow up with a latex fetish.

Enquist et al realize lactation fetishes offer a natural test of this hypothesis. Children with younger siblings will see a lot of breastfeeding going on during their critical window; children without younger siblings will see less. Since it’s easy to ask people how many siblings they have, you can see if younger siblings correlate with lactation fetishes.

They survey some online lactation fetishist communities and ask everyone how many older and younger siblings they have. Although by chance we would expect an equal number of both, in fact the fetishists have many more younger than older siblings:

They interpret this as support for their critical window theory.

But their graph looks a lot like this graph of SSC readers:

I use the opposite order they do, but both graphs show the same thing: more older than younger siblings.

I interpret the SSC data as showing a birth order effect on intellectual curiosity. But if this is true, it casts Enquist et al’s results into doubt. The trait I’m calling “intellectual curiosity” is linked to openness to experience. Could it also cause people to be more curious and open about fetishes, or more likely to join online communities about those fetishes?

I decided to test these hypotheses using the SSC 2019 Survey, which contained data on participants’ fetishes. I looked into lactation to replicate the Enquist results, but also into diaper fetishes, since that seemed like another fetish where exposure to the relevant stimulus would depend a lot on having a baby in the house. I also looked at latex, foot, bondage, masochism, and furry fetishes as control groups. Here are the results:

All fetishes had more older than younger siblings. But the difference was only significant in lactation fetish (p = 0.01). The difference between significant and nonsignificant results is not always itself significant, and I’m not sure how I would properly analyze this given the many different comparisons (some of which I made after seeing the data). i lean towards not being very impressed with the critical window theory on this metric.

But here’s another potential test: compare people with younger siblings to people with no siblings.

In Enquist et al’s model, the presence of a younger sibling causes the lactation fetish. In my model, the presence of an older sibling suppresses openness to experience and prevents fetish formation. So if only children behaved more like older siblings, that would support my model; if they behaved more like younger children, it would support Enquist et al.

I compared participants with no siblings to participants with a younger sibling in the critical window of less than five years age gap. Here are the results:

No difference. This suggests that having a younger sibling does not make you more likely to develop a baby-related fetish, which suggests it’s just that having an older sibling makes you less likely to develop it. This casts doubt on any simple critical window theory of fetishes, and makes it more likely that Enquist et al were just detecting the same birth order effects on openness to experience that can be found in many unusual communities.

These data are thanks to people who graciously revealed their deepest secrets for the cause of science; please be kind and don’t make fun of them or call them gross in the comments. Although I’ve made every other part of the survey publicly available, given the sensitivity of fetishes I’m keeping these particular answers private. If you are a professional researcher (or an amateur researcher with a good track record of professionalism and data integrity), and you want to test these results, please email me at scott[at]slatestarcodex[dot]com and we can discuss how to make that happen.

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95 Responses to A Critical Period For Lactation Fetishes

  1. Le Maistre Chat says:

    Oh, OK, this is about science.
    The title had me thinking that you’d be a rabble-rouser at a podium declaring that “the critical period for lactation fetishes is now!

    • acymetric says:

      This was 100% my thought when I first saw the title.

      I thought maybe it was going to be related to polices/norms on breastfeeding in public or something.

  2. Near says:

    Is there a reason why this suggested critical period is so early on, rather than during or around puberty? I see a lot more potential for interesting results if you were able to discern what someone is exposed to later on when their sexuality is actually forming.

    • Le Maistre Chat says:

      If the critical period is around puberty, you’d expect to be into whatever your first love was into. Then the question is what caused their fetish…

      • albertborrow says:

        “First love” is an interesting euphemism for internet pornography. Don’t think I’ve heard that one before…

        • acymetric says:

          Yeah, I think there is probably a lot of potential for imprinting during pre-teen/early teen years before actually engaging in any sexually charged contact with a partner. This would hold even without internet porn.

          Most people spend at least some time wanting to hook up with other people before they actually do it.

        • Le Maistre Chat says:

          🙂
          I was thinking that there must be a chain of regress back to someone who had each of these fetishes before the internet existed. My impression is that pre-internet porn minors would be able to get their hands on was quite vanilla (to say nothing of tending toward softcore like Playboy, since there’s no reason you can’t have kinky softcore porn).

    • keaswaran says:

      I think there’s no particular reason to think that fetish critical periods would be in early childhood, rather than middle childhood, puberty, or adolescence. But if there *is* a critical period, it could be at any of these times. And the early childhood one has a nice hypothesis for how it might work, that can be easily tested by looking for birth order effects.

      So it’s not that this critical period is particularly likely, but just that out of any critical period hypothesis that makes any sense, it’s the easiest one to test. (Of course, there’s no particular reason that there should be a critical period, or that it should make sense.)

    • SaiNushi says:

      I know I’m only a single data point, but… I started having fantasies with the same sort of theme as my sexual fetish long before I became sexually interested, let alone sexually active. For the timing, first fantasy involving the fetish in a non-sexual context, I was about 10 years old. First sexual fantasy involving the fetish, I was 13. First sex, I was 19. First porn, uh… 22 I think. First realization that my earlier fantasies indicated my adult fetish… again I think I was 22.

      Again, I realize, this is only anecdotal, but it does point to at least some cases of fetishes forming long before anything sexual gets involved.

    • Watchman says:

      Anecdotal, but my particular fetish manifested before puberty, and others I’ve interacted with (online forums rather than exercising the fetish) report similar experiences. Not universal though, as some with the fetish came to it in adulthood, through partners or in other ways.

    • Ozy Frantz says:

      It is not at all uncommon for fetishists to be interested in their fetish well before puberty. For example, lots of people who grow up to be into bondage really liked tying-up games as children, lots of hypno fetishes rewatch Jungle Book over and over again, lots of furries had crushes on anthropomorphic animals in cartoons, lots of crossdressers felt a yearning desire to wear cross-sex clothing, etc.

      • acymetric says:

        Aren’t all of those things fairly common among kids generally? Maybe not so much tying-up games (what is a game kids play that involves tying up…do these kids even know how to tie things yet?) but rewatching Jungle Book, crushes on Babs Bunny or whatever (there is probably a better example but I can’t think of one off the top of my head), and playing dress-up in the opposite gender’s clothing all seem pretty par for the course to me, and I grew up in a pretty conservative household where if there were concerns of 4 year old me wearing my friend’s princess dress or ballerina outfit indicating any unusual sexual preferences it would have been quashed and how.

        This seems mostly like overactive pattern matching…kind of like the parents mentioned in another post somewhere who “always knew” their kid was gay.

        • Whie says:

          I think when someone says that watching Jungle Book was evidence of their hypnosis fetish they usually mean that they knew, at the time, that they were particularly interested in the part with the snake hypnotizing someone.

          So lots of people watched the Jungle Book a lot, but not all of them remember thinking the part with the hypnosis was special to them.

          It’s not necessarily looking back for anything that could explain the fetish, it’s having specific examples of something being special to you when you were 5, and when you were 7, and when you were 9, and when you were 11, and when you were 13, and then at 15 you learned that the word people use to describe what you were currently experiencing was “fetish”.

  3. Michael Watts says:

    They survey some online lactation fetishist communities and ask everyone how many older and younger siblings they have. Although by chance we would expect an equal number of both…

    Is this actually true? I was dubious about it when you relied on this assumption for birth order effects, and I’m more dubious now that you seem to have conclusively disproven it. Why would we expect online communities to have an equal number of older/younger siblings by chance? Aren’t younger siblings systematically younger than older ones are? If I’m 20 and my brother is 4, are we really going to be members of an equal number of online communities? What about real-world social groups?

    I think the answers to those two questions are no and no, implying that pretty much every group that exists will have older siblings overrepresented compared to younger siblings. And lo and behold, that’s exactly what you just documented. Where did we get the idea that “by chance” we should see something different?

    Put another way, imagine that for a period of, say, 50 years, you surveyed every member of a community who was 35 that year. That would put you on stronger ground for expecting an even birth order distribution. But you’re surveying every member who is in the community, regardless of their age, at a single point in time. That isn’t the same thing.

    • James says:

      But I think the pairs of siblings who are respectively 20 and 4 will be matched by pairs of siblings with the same age gap but born earlier, who are (for instance) 36 and 20. This seems like it should balance out… except for when we get to ages when the older ones start to die off. And there’s population growth, I guess, which would skew things in favour of a younger cohort, but that doesn’t seem very significant.

    • Athenae Galea says:

      First of all, theoretically I don’t think I agree. Assuming constant birth rate (which we mostly can in America over the relevant period), there would be as many older as younger siblings who were the same age, because your younger brother will be 20 for exactly as long as you were, and with no change in the birth rate this means there will be as many 20-year-old younger siblings as older siblings (in families with two children). The only issue would be whether those whose siblings have died answered including them. The question was “How many [older/younger] siblings do you have?” so I’m honestly not sure. Though I think this would have a negligible impact on the results.
      Then, empirically, we have these results, where the blue line is those who are younger siblings and the orange line those who are older (in families with two children). That looks far more like a scale than a translate to me.
      Edit: I mean, actually it looks like a scale and a translate of around… 3 or 4 years? Eyeballing this really isn’t enough for the details. This is really weird and I’m not sure what to make of it. I don’t think your proposed mechanism works, but I’m not sure what it would be instead.

    • J. Mensch says:

      Why would we expect online communities to have an equal number of older/younger siblings by chance? Aren’t younger siblings systematically younger than older ones are? If I’m 20 and my brother is 4, are we really going to be members of an equal number of online communities? What about real-world social groups?

      I’d like the next survey to find out what sort of people arrive at this conclusion.

      Edit: This isn’t supposed to imply it’s an obviously dumb conclusion. It’s just something several commenters said on the last post too, and I found it strange how common it was for what seems to me a subtle (and incorrect) explanation.

      • acymetric says:

        Maybe I can provide some insight, as I realized my mistake while writing a response to another post explaining why I arrived at that conclusion.

        The issue is thinking of it in terms of the specific younger siblings of actual respondents, rather than considering people who are younger siblings in the general population. If our pool of younger siblings in the survey was limited to the younger siblings of the survey respondents, this conclusion would hold (because a decent number of those siblings would be too young to be reading this site). We aren’t though, we are looking at the overall population of younger siblings.

        In other words, if you took the respondents who picked “older sibling” and then surveyed their younger siblings, you would expect a higher percentage of older siblings to younger. I don’t know if I’m explaining this well and there’s probably a simple term for this kind of error in statistics/data analysis but hopefully this sheds some light.

      • googolplexbyte says:

        It’s the classic inside view perspective vs. outside view perspective, that is the most common source of confusion in all things.

    • ZachJacobi says:

      I had the same thought and decided to write a script to check on it. Respondents with a single younger sibling were, on average, ~1.2 years older than respondents with a single older sibling.

      The actual numbers:
      Average age: 32.54
      Average age with 1 older sibling: 31.24
      Average age with 1 younger sibling: 32.43

      There are probably simulations we could do with the age distributions to see how much this matters, but I’m running on three hours sleep right now and can’t quite figure out how to do them. I’m happy to share the Python code I have so far with anyone who wants to take this further.

      (Also, a minor complaint: to analyze this in Python I had to replace the commas in the data with the unicode fixed width comma, “,”, because Excel doesn’t seem to have a TSV export and commas in the answers absolutely wreck any attempt to do a CSV import into Python. Scott, can you release future survey responses in TSV format?)

    • abellia says:

      Simply put, not a random sample.

  4. Luke Perrin says:

    Perhaps having an older sibling making fun of you whenever you do something weird teaches you to make orthodox choices?

    • Joseph1 says:

      I think what you said is very true. But should be expanded:
      Not only older siblings, but older people/peers.
      Not only something weird, but anything elders/peers seem to do better.
      Not only ‘orthodox’, but ‘safe’ in general.
      This whole discussion should go beyond ‘intrafamily rivalry’ to include rivalry in whatever sphere. In other words, students who are born in the latter months of each year and are younger than their peers in a given school class. Also, students/etc. who physically mature later than peers and find it more difficult to assert themselves vis a vis stronger/larger(smarter?) peers.
      There are diverse circumstances that position people as the strongest in a given peer group. And peer groups other than families are also important.

  5. Basil Marte says:

    Thrifty for a phenotype.
    I would have suggested on yesterday’s post that perhaps the presence of an older sibling somehow shifted the person along the autypal*/schizotypal dimension, and SSC selected along that, but today’s post disproves that idea.
    *: To make the diametrical hypothesis more symmetrical, as schizophrenia is the dysfunctional failure mode of schizotypy, why not say that autism is the low-functioning failure mode of autypy?

    • vaticidalprophet says:

      Regardless of whether there’s any merit to the idea, it’d be interesting to hear about (if nothing else, for how you interpret ‘autypy’ and schizotypy as interacting).

  6. gkai says:

    I don’t know what the consensus is on self-introspection regarding psychological traits and their explanation, if any (crap? somewhat usefull? reliable?).
    Personally, I trust it a lot, I think the amount of info you have on yourself trump the issue of decreased objectivity about a personal subject (yourself is quite a personal subject).

    So, based on self-introspection, I believe the “critical window effect” have very limited credibility.
    I just don’t feel my pre-sexual experience (<8-10 year old let's say) had any influence on fetish or other sexual preferences later on.

    This is a safe bet, given the tendency on education/shared environment to play very little role in any outcome, but even more than that, as sexuality is really personal, I think children in western families are "on their own" there even more than for academic orientation, lifestyle, and so on.
    So, apart from varying availability of porn material (which may be quite standardised now, with internet meaning everything is available), how does family environment could affect any sexual outcome? I think it's innate (again, safe bet), with a lot of chaos in specific fetish due to self-amplifying loops that can occur during sexuality onset.

    Even lumping fetishes into categories is doubtful: you have a general fetish cluster for sure, in the sense that having one increase the chance of having another (indicating an underlying fetish tendency), but is baby-related fetishes a meaningful category? For this lactation/diaper pair should be much more correlated than other pairs? Not sure it is the case….

  7. Rachael says:

    “During childhood, you have a critical period (maybe ages 1 to 5) where you figure out what sex is.”
    That seems a bit early. I had no idea what sex was at 5, and I have a 5yo now and I’m pretty sure she doesn’t either.

    • vV_Vv says:

      Conscious understanding of sexuality appears later, but sexual orientation might develop in early childhood.

      There are some controversial studies that claim that it is possible to detect homosexuality in children around age 5, and since we know that homosexuality is not strongly heritable, this suggests that it might be caused by environmental influences (or random development errors) in early childhood, and other paraphilias might have a similar cases. However, it is also possible that these studies are crap and sexual orientation forms much later, maybe even after puberty.

      • orin says:

        I don’t know about orientation, but at least for fetishes it seems somewhat more plausible to me as a prior to assume that these kinds of things are imprinted during peak hormone levels, around puberty.

        • keaswaran says:

          How many people have stable fetishes for their whole sexual life? I had anecdotally supposed that it was far more common for people’s fetishes to change in adulthood than for their orientation to change in adulthood, but I definitely don’t know for sure.

        • Trofim_Lysenko says:

          I can only comment on what I’ve observed in online communities with a strong fetish/paraphilia sub-community, such as Furries, but there you see quite a bit of change in both directions: Some will edge towards more and more extreme forms of kink over time, while others will get tired of them and move towards less extreme forms or become disinterested in the sexual aspects of the Furry subculture entirely (some of those lose -all- interest, some do not).

          It’s tough to say whether this pattern holds true for actual behavior offline with partners though. My impression is that A) the “real” fetishes (BDSM, etc, stuff that can be experimented with in the real world) are more stable than the extreme fantasy ones, and that B) there is often a pretty big gap between sexual orientation and fetishes when consuming online porn and engaging in online role-play versus sexual orientation and fetishes offline. A LOT more guys who are happily heterosexual offline experimenting with bisexuality online, with other-gendered characters, etc.

      • Douglas Knight says:

        People believe that (male) orientation is set at an early age because gay men and their parents say “I always knew.” This has nothing to do with academic studies. But there are academic studies that collate what gay men and their parents say. They really do systematically say that. That should not be at all controversial; it’s just confirming what we already know people say. The problem is not what they say in adulthood, but whether we should trust human memory. Here is a study that replaces memory with videotapes. It has serious problems with selection bias and should be carefully replicated, but it’s a good start.

    • TheContinentalOp says:

      The inciting incident for my (non-lactation/diaper) fetish occurred when I was 4.

    • bullseye says:

      I don’t have a fetish, but I started liking redheads a few years before I had any sexual interest.

    • rlms says:

      I interpreted that bit as Freudianish, where psychosexual development occurs before 6, then goes latent until puberty.

      • Picador says:

        Yeah, I think that’s the theory. It certainly accords with my own memories. Little kids get up to all kinds, in thought and often in deed. Then they get a little older, absorb some of the social taboos around sex, and repress all that stuff, often to the point of forgetting about it altogether.

        Surely everyone — gay, straight, kinky, vanilla, whatever — has a memory from early childhood of seeing something (a comic book, a movie, a picture) that was VERY INTERESTING to them, and that was consistent with later sexual preferences. This doesn’t mean that they were “sexual” per se as young children, but there’s an obvious causal link.

        To choose just one example, a lot of little boys (and girls!) who saw Princess Leia all chained up in that harem girl outfit certainly thought it was VERY INTERESTING, and later as sexually active adolescents and adults found that their own preferences aligned with that kind of imagery. This is not an accident. Culture, and specifically the culture we’re exposed to in early childhood, is hugely formative of our sexual preferences. I thought this was uncontroversial. This is just one of the many reasons why sexual practices vary so greatly from one time and place to another, in ways that are inconveniently inconsistent with our own culture’s bizarre orthodoxies about sexual preference being hard-coded at birth into one of two or three fixed categories.

  8. I commented about similar issues regarding incest on the Age Gaps And Birth Order Effects Article. I might as well re post in here
    I have been thinking about incest taboo lately and the way that it might interact with birth order number of Children. I have a theory that the prevalence of romanticized incest in Japanese media might be related to the low birthrate and people not having actual siblings to relate incest to. Do you have any data on this and do you think you could inquire about in on your next survey?

    • Tarpitz says:

      I too suspect that incest fetishes are vastly more common in people without siblings of the gender(s) they’re attracted to.

  9. BlindKungFuMaster says:

    Hey, lactation fetishists! How do feel about your personal data being milked for science? I bet in the next post Scott will stomp all over the foot fetishists. Etc, etc, …

    I hereby express my gratitude to all fetishists who made this great post possible.

  10. fion says:

    Typo: “I compared participants with no siblings to participants, to participants with a younger sibling”. Repetition of “to participants”.

  11. vV_Vv says:

    I interpret the SSC data as showing a birth order effect on intellectual curiosity. But if this is true, it casts Enquist et al’s results into doubt. The trait I’m calling “intellectual curiosity” is linked to openness to experience. Could it also cause people to be more curious and open about fetishes, or more likely to join online communities about those fetishes?

    Or there is a birth order effect on participating to online communities and/or responding to surveys.

    All fetishes had more older than younger siblings. … No difference. This suggests that having a younger sibling does not make you more likely to develop a baby-related fetish, which suggests it’s just that having an older sibling makes you less likely to develop it.

    According to Wikipedia, an opposite results has been observed for male homosexuality: gay men are more likely to have older brothers (older sisters don’t matter, apparently).

    • Rachael says:

      Scott covered the thing about gay men with older brothers in the previous post to which this one is a follow-up, so it’s not news to him.

  12. Furslid says:

    Scott. We see the same percentage of firstborn and only children have lactation fetishes. Do we see the same percentage for non-baby fetishes?

  13. BlorgSplorg says:

    N=1. Am a diaper fetishist and a cross-dressing fetishist.

    I remember wanting to be back in diapers at a very young age (3 maybe?). Also I remember wanting to be a girl at a young age, pretending to be female characters in cartoons at maybe 5 years old. As a teenager, and especially after getting unfettered access to the internet, these grew into fetishes. Lactation and other related fetishes came into play as a result of internet content cross-promoting them to diaper fetishists.

    I have a baby sister that is less than two years younger than me. I psychoanalyze myself as learning that that was what I had to be to get love.

  14. throwaway2305 says:

    Here’s a discussion on this finding in a lactation fetishist subreddit, for that 9% of us: https://www.reddit.com/r/AdultBreastfeeding/comments/bpbvxl/survey_having_a_younger_sibling_does_not_make_you/

  15. aphyer says:

    Is it possible that for e.g. some confusing demographic reason/lying on surveys, ALL surveys will show more older than younger siblings? Are there any surveys that ask about siblings on a population where we dont expect any sibling difference?

  16. jamestillman7 says:

    What about the hypothesis that older siblings are more confident, rather than more intellectually curious, as the primary driver explaining the same data?

    I can easily tell a just so story of why older siblings would be more confident — frequently the best at everything of their siblings, and so on.

    If you’re more confident, then you might be more willing to admit (in an online survey) that you have a lactation fetish, because, well, even in an anonymized online survey sometimes people are a bit reluctant.

    And if you’re more confident, then you might be more willing to just pursue stuff just because you’re interested in it. The mythical older sibling who might make fun of you won’t be there.

    I dunno.

  17. Anatoly says:

    “Older siblings more likely“.

  18. Omaha1 says:

    Have you considered effects from exposure to infants at day care? My adult son who has Fragile X Syndrome (moderate mental retardation with autistic tendencies) seemed to develop a diaper fetish at a very young age, like six or seven. He had no younger sibs. He wanted me to buy diapers for his stuffed animals and was extremely fixated on them. He doesn’t ask for adult diapers at age 33, but now he has a thing for belly buttons (I catch him looking at YouTube every now and then). I don’t know where he would have gotten that although he might be confused about female anatomy, thinking belly button = vagina.

  19. sabre51 says:

    Seriously… I love this blog. Where else are you going to read about how big data is debunking naive psych theories, the problems with science, and then original research on sexual fetishes?

    In your annual predictions you always put “I will continue writing SlateStarCodex?”. May that number always be 100%.

  20. Ttar says:

    The real question: where are all the younger siblings hanging out? Presumably somewhere incredibly boring?

    • keaswaran says:

      Maybe younger siblings are more likely to be lurkers and older siblings are more likely to answer surveys.

      • Picador says:

        This strikes me as very likely.

        I’ve spent most of my life among overachievers, and as a second son I’m in a distinct minority. If there are other younger siblings present in those groups, they don’t do much to make their presence known.

  21. Desertopa says:

    Although it only amounts to a sample size of one, I personally have a fetish (the nature of which I would prefer not to describe publicly, but which I may reveal via private conversation,) which I acquired based on an experience around the time I turned eight years old. The specifics allow me to be highly confident that the fetish traces back to that experience, and not earlier or later.

    From conversations with a number of people who share the same fetish, I have found that in many if not all cases, the fetish was solidified in puberty when they began to sexualize what had already become a sort of obsession in a nonsexual way, and for some of them, this obsession formed earlier than it did for me, while for others, it formed later. So, on that basis, I am very much inclined to doubt the whole “critical period” hypothesis, except possibly in the sense that the “critical period” might be the entire period before puberty. Even that is questionable, since it’s hard to clearly differentiate fetishes discovered post-puberty from fetishes formed post-puberty. My strong suspicion though, based on conversations with people about a wide variety of fetishes, is that fetishes can in fact be formed, rather than discovered, post-puberty.

    • throwaway248 says:

      I don’t know if this is the same one, but I’ll say it with this throwaway. I have a vomit fetish, and I’ve definitely had it since I was really little, although I had not idea what it was. I remember one time I was playing with my best friend, probably around age 6, and my sister was throwing up in the other room, and I said to my friend, “Isn’t it weird that throw up gives you a feeling in your vagina?” I had no idea what that feeling was, but definitely significantly before puberty I figured out that it was embarrassing.

  22. Erl137 says:

    In bdsm communities, the rule of thumb is that the population divides into four roughly equal-sized groups: those who’ve known about their kinks since forever; those who developed their kinks with the onset of puberty; those who developed their kinks with the onset of adulthood; and the later-in-life bloomers.

    Rules of thumb are often inaccurate; this one might simply impose artificial bins on a continuous spectrum; and it’s hard to distinguish between someone who’s had a kink for decades and just figured it out and someone who’s discovered it later in life based solely on self-report.

    But this model would actually line up quite well with an underlying “openness” variable. If developing a fetish is a question of being open to a new sexual frame or experience, then it’s easy to imagine it occurring at different points in life; on the other hand, in the crucial period model, literally everyone was . . . spanked as a child/watched Indiana Jones/whatever, and in denial for a variable length of time? That seems kind of forced.

    So I find this result pretty interesting!

    • muskwalker says:

      But this model would actually line up quite well with an underlying “openness” variable. If developing a fetish is a question of being open to a new sexual frame or experience, then it’s easy to imagine it occurring at different points in life; on the other hand, in the crucial period model, literally everyone was . . . spanked as a child/watched Indiana Jones/whatever, and in denial for a variable length of time? That seems kind of forced.

      Speaking of openness and variables, I think the variation in kink intensity needs to be accounted for in studies like this as well… a fetish community is going to have everyone from “I can be turned on by this, when it’s done well”, to “I’d rather have this when I play than not have it”, to “it isn’t a sexual experience for me unless this is involved” and “this is always a turn-on, even in otherwise non-sexual contexts”. The latter two are the more central examples of “fetish” (though I imagine may be less common overall).

      Apparently halfway through the survey they added a question “How strong is your attraction to lactating or breastfeeding women? [Forced choice between 0 and 10]” but I don’t see that they used it for anything anywhere.

    • keaswaran says:

      Is there any substantial subset that used to have a kink but no longer does? Or is it a pretty good assumption that if a person at any point in their life identifies as having a particular kink, that they will continue to do so thereafter, even if they discover other kinks?

      • Erl137 says:

        Anecdotally I’ve read a couple of accounts (maybe just one account?), but it’s very hard to quantify the population. There are lots of reasons to drop out of kink communities or kink self-reporting, and no deep longitudinal studies that I’m aware of—though it’s been a little while since I was keeping abreast of the research.

      • gkai says:

        Anecdotal too, but I would say yes. It evolves and grow, mostly new related fetishes being added and some reducing/dissapearing.
        I really link it to preference for certain types of women, it’s the same type of thing imho, and this is common and not stigmatised at all (or so I think, it changes everyday so it may be politically incorrect now).
        the type of woman you are especially attracted to change with time. It did for me me at least…

  23. Jeffery Mewtamer says:

    I too kind of question the assumption that we should expect a fifty-fifty split of older and younger siblings in online populations. Anything, part of me feels like we should expect more younger siblings online due to the tendency of younger people to be more comfortable with newer technology and thus having a larger online presence. Though perhaps that doesn’t matter much for siblings that are eclose in age and is only significant for siblings with large age gaps.

    I’m also curious what, if any, role other youths in a household have on birth order effects.

    For most of my life, I’ve lived in a household with at least three generations under one roof, and even now, the only family I cohabitate with is a niece as I’m a childless bachelor and all of my parents, grandparents, and siblings are dead.

    My older siblings were 18 and 14 years my senior, and my sister’s daughters are only 6 and 8 years my junior. My sister never permanently moved out, so I grew up under the same roof as my nieces, and even shared a room with both of them for much of late childhood and my preteen years.

    So, would one expect me to be most like a youngest child(what I am literally), more like an only child due to the massive age gap between me and my siblings, more like an eldest child because I’m much closer in age to my nieces and we were raised more like siblings, or more like a middle child due to having actual older siblings and surrogate younger siblings in my nieces?

    Actually, have there been many studies on cohabitating children with non-sibling blood relations? Or youths in boarding schools or other environments where non-blood related children cohabitate en masse? The latter interests me as, on top of my possibly unusual home life, I attended a school where most of the students boarded during the week and went home on weekends from grade 4 through my highschool graduation.

    • RavenclawPrefect says:

      Part of me feels like we should expect more younger siblings online due to the tendency of younger people to be more comfortable with newer technology and thus having a larger online presence.

      The set of {people who are younger siblings} does not have an especially different age distribution from {people who are older siblings}; the difference within each family is offset by the group of people at the older end where the younger siblings are more likely to still be alive.

      To see this more clearly, suppose there are 100 families separated by a year each, which have two children with an age gap of two years; the lifespan of every person is 100 years old. You have a 0/2 year old pair of siblings, and a 1/3 pair, and 2/4, and so on, up to a 98 and 99 year old whose older siblings are no longer alive. (You also have a 1yo and an infant whose younger siblings are not yet born.) Then there is one older sibling and one younger sibling at each age.

    • Nornagest says:

      Anything, part of me feels like we should expect more younger siblings online due to the tendency of younger people to be more comfortable with newer technology and thus having a larger online presence.

      At the risk of belaboring the obvious, younger siblings are younger relative to their siblings, not systematically younger relative to the population. This does break down when you start talking about very young people, since their siblings wouldn’t have had a chance to be born yet — but the SSC sample is mostly late adolescent or older, and gaps between siblings of 15+ years are rare these days. It also breaks down if the population’s composition changes much over that time, but it’s pretty stable in first-world countries, where we’d expect most of the sample to be coming from.

      • acymetric says:

        I know this was the mistake I was making when I initially had the same thought as Jeffrey (and quite a few others). I assume this is where most people are making their mistake.

  24. septologist says:

    a different hypothesis: having older siblings (in particular brothers) is likely to make you less masculine, so you end up with a less masculine sexuality. strong fetishes are more typical for masculine sexuality.

    (i would’ve also said that the more subby fetishes are less affected by that because they’re less masculine to begin with, but before seeing the results, i would’ve also classified diapers as a subby fetish.)

    scott, does the effect of a reduced likelihood to have one of those fetishes hold equally well for only older sisters?

    • Watchman says:

      How do we come to the equation masculinity = higher liklihood of fetishes? I’d point out that highly masculine environments (military, sports teams (male), traditional masculine industries are in fact normally regarded as intolerant of deviation, so masculinity as displayed doesn’t support this.

      • Nornagest says:

        It’s very old, very stable conventional wisdom in sex research that paraphilias are more common in guys — some sources I’ve read say exclusive to them, although I’m pretty sure that’s wrong. But that older paraphilia research is usually limited to pretty strong fetishes — the type that’d be likely to come to a psychologist’s attention, so we’d be talking people that straight-up can’t get aroused without involving, say, feet, or balloons. It’s not clear to me whether that’d still hold when we’re talking people who just like to get tied to the bedposts every once in a while.

        • Le Maistre Chat says:

          It’s not clear to me whether that’d still hold when we’re talking people who just like to get tied to the bedposts every once in a while.

          Obviously it doesn’t. 😐

        • acymetric says:

          That some say it is exclusively male makes me highly skeptical of the whole enterprise just based on personal observation/experience. For the ones that are more measured and go with “more common” how much more common do they tend to be?

          I’m also having trouble getting a firm grasp on the difference between paraphilia and a fetish.

          • Nornagest says:

            Well, going by DSM definitions is always kind of fraught, but paraphilias prior to DSM V used to require that the fetish “cause clinically significant distress or impairment in social, occupational, or other important areas of functioning”. So an irresistible urge to get your dick out at a high school football game would count, if it subsequently got you run down by the cops, but getting your tits out at Mardi Gras wouldn’t.

            DSM V instead uses that definition for a “paraphilic disorder”, while leaving “paraphilia” undefined. FWIW, all abovementioned sources re: guys predate DSM V.

        • Ozy Frantz says:

          My personal suspicion is that women and men are equally likely to have paraphilias, but:

          (a) women are more likely to be repressed about their paraphilias;
          (b) women are less likely to report having paraphilias even if aware of them;
          (c) women are less likely to commit paraphilia-related crime;
          (d) due to a combination of (a) and (b), paraphilias are defined along a male model, and thus while ‘I get off on contemplating a society in which some men’s sexuality is oppressed and controlled but then they go into heat and are no longer responsible for their actions and get gangbanged by a dozen men with dog dicks’ is clearly Some Manner Of Paraphilia there is no paraphiliac category for it in the DSM.

          • acymetric says:

            This is pretty much what I thought…I might add an (e) that there is some cultural bias that would lead to underdiagnosis of women when a medical professional is confronted with it. Not exactly the same, but a similar bias to the one that makes people say both “homosexuality is disgusting and terrible” but also “those two girls making out is hawt“.

          • Picador says:

            “while ‘I get off on contemplating a society in which some men’s sexuality is oppressed and controlled but then they go into heat and are no longer responsible for their actions and get gangbanged by a dozen men with dog dicks’ is clearly Some Manner Of Paraphilia there is no paraphiliac category for it in the DSM.”

            True. The DSM diagnostic checklist requires it to be at least two dozen.

  25. muskwalker says:

    It’s interesting that the study’s question was “Do you find lactating or breast-feeding women sexually attractive? [Yes/No]”, which (aside from how, out of context, it seems to be testing whether you’re turned off by the condition) seems like a very specific subset of ‘lactation fetish’—which is something that needn’t be about attraction to the woman per se, or even attraction to a woman at all. (I do understand that doing this allows them to relate it to their specific hypothesis.)

    I wonder how many other people checking ‘Lactation’ under the SSC question “Which of the following fetishes do you find at least a little bit sexy?” would have said ‘no’ to the researchers’ question.

    • Furslid says:

      Yeah, this seems to be a little odd phrasing. I might answer yes to that question while being in general indifferent to lactation with a slight preference against. Better phrasing might be “Cetaris paribus, do you find a lactating woman [ ] more, [ ] less, or [ ] equally sexually attractive.”

      • acymetric says:

        If you’re trying to improve phrasing of a survey question for the general public, start by not including the phrase “cetaris paribus”. 😉

      • muskwalker says:

        This phrasing is slightly more focused—but it’s still oriented towards the perspective that a lactation fetish must involve being attracted to a lactating woman, which, now that I look at it further, doesn’t seem to follow from their “sexual imprinting” hypothesis at all. It adds an unspoken presupposition that the child is imprinting onto the role of the younger sibling (who pursues the milk) and not, say, the mother (who produces it).

        (I don’t move in lactation-centric circles so I don’t have a high N, but I feel like the lactation fetishists I’m most familiar with have seemed far more interested in being the one who is lactating or nursed from.)

        • muskwalker says:

          I feel like the lactation fetishists I’m most familiar with have seemed far more interested in being the one who is lactating or nursed from.

          Did an informal poll on NSFW Twitter to confirm this feeling. Ran for 24 hours, got 28 respondents. Didn’t get a preference as strong as I was expecting, but it does seem approximately as common.

          “Lactation! Which do you like *MOST*? #poll”
          8 (29%) Lactating for others
          6 (21%) Being lactated for
          3 (11%) Too close to call
          11 (39%) Not into lactation

    • chridd says:

      I’d worry about the opposite problem—that people who don’t have a lactation fetish would answer “yes” (e.g. because they find most women sexually attractive and breast-feeding women aren’t an exception; or because they find it only a little sexy, but not enough to be considered a fetish, though those would also answer yes to SSC’s question). (Of course, it’s also possible for the question to have both problems.)

  26. 10240 says:

    Ratio of firstborn to lastborn siblings (in sibships of two) with each fetish

    Have you controlled for firstborns being more common among SSC readers in general? The ratios in that chart are smaller than the ratios among SSC readers as a whole.

  27. Owen George says:

    It seems like the baseline ratio for ssc readers is around 2.5 (of first-born to last-born in families of two). If the ratio of lactation fetishes is only 1.4 among the ssc readership, isn’t that lower than baseline? And therefore it would actually imply that younger siblings might be the ones who are more likely to have fetishes (conditional on being an ssc reader). Am I missing something?

  28. Phigment says:

    It feels to me like you may be measuring something besides what you think you are measuring.

    Like, if you keep taking surveys of different things, and older siblings are always higher probability of engaging in those things, you may have discovered that older siblings are systematically more likely to participate in surveys than younger siblings, or something of that nature.

    Sort of like people noticing that if you do all your psychology research by recruiting groups of college undergraduates in the USA, you get a fairly abnormal group of people compared to the whole population of humans in the world.

    Also, and probably unrelated, it strikes me that the distribution of older and younger siblings must be in a pretty weird state of change for the last few decades, as expected family sizes are shifting. My grandfather was one of ten children, and that was a big group but not strange. Nowadays, families with more than three kids in the USA seem to be a definite minority, and families with only 1-2 children are very common.

    We could be moving over time from a state where, say, 25% of people you meet are oldest children to a state where 50% are pretty easily. Wonder how that affect these things, and how it affects culture.

    • Tenacious D says:

      Interesting point about the changing distribution of oldest children.

    • deciusbrutus says:

      Among people with exactly one sibling, exactly half of them are firstborn.

      We might be seeing differences in the distribution of number of siblings, but the population as a whole is going to be perfectly evenly divided on birth order.

  29. Peter Shenkin says:

    For additional confirmation, try to see if the trend disappears for people born before about 1965. From about the mid-1940s till then, bottle feeding was very common, so I’d expect the correlation with age, as well as the incidence of this fetish to be less in that peer group.

    Or even, ask whether their mother breast- or bottle-fed her kids.

    -P.

    • bullseye says:

      I have no idea whether I was breastfed. Do most people know whether they were breastfed?

    • Anthony says:

      1965 is too early a cutoff date. I was born a little while later than that, and my sister in the early 1970s, and my mother’s preference to breast-feed was somewhat uncommon. (White, middle-class, eastern seaboard of US.)

  30. deciusbrutus says:

    The sample “SSC readers” is already biased towards lactation fetishists and older siblings; why would you trust that the results of comparing those things things within the sample will generalize to people?

  31. kastaka says:

    Hmm. Birth order effect on openness makes me wonder if it’s a scarcity-environment thing?

    A firstborn has a more abundant environment both in the womb and in the very early stages than a second child within a few years of the first, and there seem to be a lot of hidden switches all over the place for ‘am I in an abundant environment or a scarcity environment?’ which switch on a lot of thrive vs survive behaviours – and intellectual curiosity / openness is an abundance-oriented behaviour.

  32. Bram Cohen says:

    Does this result differ if you only look at older brothers/sisters? That might provide a hint as to whether this is related to the homosexuality birth order effect.

  33. Casual Reader says:

    I have been reading Scott’s older articles instead of his newer ones, and so I didn’t know about the survey until just now. That’s a shame. I rarely get to talk about my fetish, and doing so would’ve been cathartic.

  34. tvt35cwm says:

    Although by chance we would expect an equal number of both, in fact the fetishists have many more younger than older siblings

    I have a feeling that something related to Zipf’s Law is involved here. I certainly wouldn’t expect equal numbers.