What it proves is it's not completely genetic. They have the same genes.
The more older brothers a man has, the greater that man's chance of being gay.
To me, cases like that really scream out, 'Hey, it's not out there. It's in here.' There's no indication that this mother is prone to raise very feminine boys because his twin is not that way.
It would be a waste of time and money to have two elections.
They're just more successful at it, because the people they're trying to have sex with are also interested in it.
Straight men tend to be shallow in terms of focusing on looks. Gay men are shallow, too. Straight men are more interested than straight women in having casual, uncommitted sex. Gay men are like that, too.
That's environment. But that's not the only environment. There's also the environment that happens to us while we?re in the womb. And scientists are realizing that environment is much more important than we ever thought it was.