I don't think that there is a gene. Otherwise, after thousands of generations, the gay gene would have been discarded as being useless because it is not reinforced through procreation. Discarded because gayness means no or very few offspring.
Prior to birth: hormones?
Post birth: relationships and bonding with the mother? Relationships with the father?
Post birth: abuse (sexual and other).
Post birth: perversion of the individual because of the availability of extreme forms of sex — innocence lost. Much like a drug addict searching for the next high leads them to more extreme sexual situations including homosexuality.
I agree with much of what you say here. I believe imprinting is a strong factor, but many straights have been successfully raised by single women. I also think there is a trend of not accepting any responsibility that seems to be native in some. The denial of traditional responsibility associated with “being a man” or “being a woman” could cause denial of manhood or womanhood itself. Likewise, those who cannot accept their same sex attraction feel they must have been born into the body of the wrong sex. Again with feelings instead of thought.
When children are young, the opposite sex is icky. We fully believed girls had cooties, whatever those were. I remember when all that changed, the day school started back and I was in 6th grade. There was something suddenly different about Lisa, whom I had known for years. I couldn’t quite put my finger on it, but I knew I wanted to. Maybe some guys still believe in cooties, who knows...
That's what I think too. There's a time in one's life, in childhood, when some experience can flip a switch in them. Needn't be an abusive experience, just whatever can be perceived in terms of sexuality, and usually is something obviously sexual or gender-related. At some time in life the mind is ready to absorb it and incline toward it or against it, and a preference is set.