You're right on one level when you say:

"Need, sorroundings, society, culture, religion all play a part in driving this."

But the things above drive *behavior* and *actions*. They don't drive the actual *desire*.

If homosexuality was a product of the above - need, surroundings etc, then homosexual children would all have homosexual siblings, as they have grown up in the same family in the same surrounds.

Your argument doesn't really hold water when you consider that homosexual children are usually just one sibling amongst heterosexual brothers and sisters.