Popcorn

On the note of parenting influence on sexuality- the Pedatric[sic] Academy of America clearly stated- in a study repeatedly backed up throughout the world-

there is no scientific evidence that abnormal parenting, sexual abuse, or other adverse life events influence sexual orientation

I think its utterly unrealistic/unbelievable to think that sexuality is not 'pre-determined'.
One of the studies that has always stuck in my mind is the birth order study.
Another is the biological/physiological differences between heterosexuals/bisexuals/ homosexuals. (Including a report that gay men have bigger penises then straight ones- thats by the by though)

A good start for anyone interested in the complex genetic and other factors currently being argued about within this area is the wiki article- which is well written and a good primer:
[ame]http://en.wikipedia.org/wiki/Biology_and_sexual_orientation[/ame]

I also think that the Kinsey scale of sexuality is probably the most acceptable means of modelling sexuality, without labelling- especially within a scientific context.