But also ask yourself: why aren’t brothers and sisters sexually attracted to each other? Is it only a cultural reinforcement? Or is there a genetic involvement that keeps heterosexual men from being attracted in response to their sisters’ pheromones? I would propose that the answer also explains why any intimate act that utilizes pheromones (even if absent lust) disgusts us to think about with our siblings.
It is generally believed that this
reflex is neither genetic (at least not in the sense that our genes are coded from birth to be disgusted by our genetically close individuals) nor societal. Completely unrelated adopted siblings have been shown to have the same reflex, as do children who are raised by the same nanny, children who grow up closely together in tribal villages (or a more modern example, kibbutzim), cousins who grow up very close (while in other cultures with greater relational distance to cousins, the reflex is absent), and so on.
I think most researchers agree that pheromones are part of the picture, basically through conditioning - if you’re “overloaded” with a person’s smells during childhood, they cause this reflex. It has been tested in a study (I will not be able to provide the link - I read about it in a newspaper more than ten years ago…) where people were told to smell different sets of (obviously worn) underwear and report their reaction. People almost invariably reported disgust at smelling the underwear of parents and siblings, while giving neutral or positive response to the others. They had no way of knowing which belonged to their close relatives, other than smell. As we don’t consciously process pheromones (I’d
so love having my family’s ability to smell who’s knocking on the door!), their disgust wasn’t activated from knowing it belonged to their close relatives either - it is a reflex.
Lastly, there’s actually a hypothesis that
, not disgustattraction, if we remove the conditioning process above. This is because people show an incredible propensity to fall for close relatives from whom they’ve been separated, especially when they don’t even know who the person is. Especially with the birth of artificial contraception (lame pun intended), it is not that uncommon for couples to find out they’re siblings, just as they ask for a marriage license. There are also several known cases of siblings who were separated, met each other as adults and even knew who the other person is, but where the disgust reflex didn’t kick in - on the other hand, the attraction seemed to be unusually strong.
Actually, the commonality of cousin romance in countries where cousins aren’t seen as “almost siblings” kind of strengthens this hypothesis, come to think of it. While both hypotheses can probably be criticized, they sound well founded to me. In my own country, marriage (and probably even more so romance) between cousins was incredibly common up to and including the 19th century - usually, they lived in different places, people traveled less, and they often didn’t meet until their teens. With the advent of the railroad, visiting relatives became easier and thus more common, and as such the imprinting we’re speaking about happened more often, causing the rate of cousin marriage to decline. We still don’t have the taboo around it that I observe among Americans - it was still not unheard of just two generations above me, so in my home village, everyone knew (or knew of) married cousins when I grew up, and it wasn’t really seen as odd in any way. I can’t think of any examples in my generation or my parents’ generation though.
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