If you include time in the womb as being one of the environment factors, then we may agree; if not, however:
Let’s suppose a physically healthy mother and father, and then consider a pregnancy, difficult or not, wherein the mother experiences substantial (+/-) emotional issues such as profound regret over being pregnant, etc.
How is it possible to discount entirely some “irregularly” in the development of the fetus pertaining to its chemistry, the growth of its wiring, etc? Can there not be some result of the mother’s mental activity in that development? Are there not occasional mistakes in nature?
Even if that's true, the gay lobby has been trying to suppress or outlaw any sort of recovery research or medical therapy, while vigorously supporting transgressive public behavior like using any bathroom, endorsing the teaching of perverted sex acts in elementary schools and demanding government assistance to obtain mutilating transgender surgery.
Time in the womb and the environmental factors associated are indeed possible contributors.
But it would not be an identifiable mutation except under extreme cicumstances. Most likely modify the resulting proteins produced by the existing alleles.
Would not discount it. But again, it’s not really a transmitted genetic trait; it’s something acquired, and possibly treated.
Mammals evolved needing two to tango. And it can’t be two with the same equipment set. Or predilection to the same equipment. Maybe could work some other way; there many examples in the lower phyla. But not ours.
No, it’s environmental. I’ve heard some jerk tried to blame it on older brothers, apparently some weird chemical thing that happens after delivering too many boys, but that jerk was written off. No, there’s no genetic cause, so, it must be environmental.