[for-q-clinton]

If it were genetic, then more than 50% of identical twins would be gay. The 50% number implies that it is not genetic since identical twins share the same genetic makeup. Or if it is genetic, then some twins can control that behavior.

Actually the article says it's a combination of genetics and environment. 50% link is a strong link and it drops to 20% with fraternal twins, so that dismisses environment as the sole source. Maybe one twin resents his mom more and had more fun with his dad--who knows.

[sobieski]

But it's not strong from a statistical point of view. These people share the same genes, so if it were genetic it should be very close to 100%. Either:

1) It's environmental
2) It's a behavior, which 50% of the people w/ this 'gene' are able to control.
3) Fraternal twins are irrelevant. They are like all other siblings. So 20% share it; well, close to 100% of fraternal siblings share the same upbringing.