So much of genetics is coincidence and unrelated associations, at lower levels. Things like the defect for sickel cell anemia happening to give you immunity to malaria, or DDT made to kill insects causing bird shells to get really thin. (although the connection there has been proven by research, I don't think they've figured out exactly what DDT does to cause it) Life is just too complicated and interwoven to predict, and the only reason it works is it tries everything and only what works sticks around to make more of that variation.
When you look at mental states, and especially preferences, it takes this to a whole new level of impossible-to-predict. Statistically proven relationships (even very small ones) regarding a person's personal preferences are almost nonexistent. Heck, just look at all the research that's been done trying (and failing miserably) to find a genetic or environmental "cause for being gay"... and THAT should be a lot easier target to track than something as (biologically) abstract as wanting to wear diapers.
It's never going to happen, you may as well treat it as random. You might be able to find a consistent percentage in the global population, but I doubt much else.
I wish I could remember an example I read awhile ago... there's a somewhat (in)famous example of a totally off-the-wall relationship that's been statistically proven and verified but utterly baffles anyone that tries to figure out the mechanic behind it. I can't remember anything of the issue, but just pulling out an on-par example, it'd be like "there's a slight preference for salted peanuts over unsalted peanuts in people that used to play tennis". It was a connection that just totally does not make sense, but had been checked and rechecked and verified to exist. (it was in a marketing research paper I read years ago, apparently there are several of these "effects" that market research has found that they know exists but can't explain) I don't suppose anyone has any idea what I'm talking about with this... it had a name too, related to the comparison. "the popcorn effect" or something like that. No idea. Anyway, it did a good job showing that it can be very hard to identify (and justify) the reason behind personal preferences.