[Antoninus]

Identical (monozygotic) twins are not eligible since it is already known that their DNA (genetic material) is the same.

If it were all nature and no nurture, studies of identical twins would reveal that in ALL cases, if one was "gay", both were. Ever seen such studies done? I know they have been--it's strange that the homo-promo cheerleaders don't trot them out more often...

[MeanWestTexan]

You know, I would love for someone to actually do such a study --- twins, no twins, gay and not gay and delve into the issue for real.

Why?

1. To answer the question for real.

2. And hypothetically, if there was a gene that made people succeptiable to being gay, it would be likely that a vaccine could be eventually created to turn it off.

All that said, I think it is largely, if not exclusively, environment and choice.