I read a serious article probably a year back which purported to explain one line of research. In summary, and without scientific jargon, the explanation was this: a male fetus in the mother's womb is treated by the mother's body as alien and attempts are made to destroy it. The mother counters this by disguising the sex. We can assume this is achieved chemically rather than dressing in party frocks. Through successive pregnancies, the mother becomes more adept at this disguise and it is thought that at some stage the disguise 'takes' and the result is a homosexual male child. This does not apply to females, note.
Statistically, you can check this because it means, if there is any truth in the idea, an overwhelming majority of gay men should be the youngest male offspring. In my own case, I am. So is my partner. In fact 90% of my close, gay, male friends fall into this category.
Do a little survey and see if the theory holds. If it does, what conclusions can you draw about religions that traditionally lead to larger families? :devil:
I should add that I've tried to research this further on the net and failed dismally, for want of meaningful keywords.