A gay friend of mine grew up in a 3-child family. He was especially close to his mother, it is true, but he is close to his father too. Family is important to him.

His brother is a politically conservative, money-making, goal-oriented straight man whom my friend is not close with. His sister is gay. They have a nephew who is also gay.

Given all that - and countless other pieces of evidence - I fail utterly to see why the idea of genetics is so difficult, so resisted, among those who feel so vehemently about homosexuality.