SwallowedaFly - I don't agree with this natural/normal v choice argument.
What about people who DO chose a sexual lifestyle different to their 'genetic' inclinations - for instance the 'political' lesbianism of the eighties etc. What about straight men and boys working as male prostitutes?
Are these forms of sexual expression invalid and therefore up for criticism in a way that someone who 'just can't help themselves is'? It's far to reductionist a view of sexual behavior and identity.
There is a reason why terms like 'men who have sex with men' exist separate to terms of identity like Gay.
Conversely, there is considerable evidence that there is a genetic predisposition towards religious belief in human beings - 'The God Gene'. So whether one believes it a benefit or not "natural" it may well be that the genetic predisposition to belief is as strong (or at least comparable) to that towards a particular form of behaviour.