How do you turn someone gay?

It is now known and accepted by most scientists that it is impossible to 'turn' someone gay, and that it has to do with birth and 'nature' as opposed to upbringing and 'nurture'.

Impossible, you can't "turn someone gay", just like it's impossible to turn someone straight like the 'gay to straight ministries'. A farcical concept wherein you either go celibate or you 'pretend' to be straight. Some people have the religious conviction to become celibate, but nobody really changes their sexual orientation.

Answer

You can't. Sexual orientation (gay, straight, bisexual) is determined mostly by genetics. Many straight men experiment with gay sex. According to the Kinsey study, about 30% of men surveyed in the mid-1940's had at least one homosexual experience to orgasm. So it's possible to convince someone to "experiment" and it's possible that a person could be bisexual, but you can't "turn" someone homosexual if they aren't already gay.