As regards politics, I think the gay being innate thing was a potentially useful idea to convince, but has now become a belief in itself, rather than anything useful. Some lesbians and gay men may find it a comforting belief, that is true, but some (like Julie Bindel who says she chose to be a lesbian) do not.
Myself, I don't much care, I'm just glad I am (quick chorus of Tom Robinson despite the fact that he never had that much to say about dykes..............).
From a scientific (and political) point of view, I think it is a mistake to continually frame it as 'why are some people gay?' -- especially given what we now know about species like bonobos where hetero and homo sex is perfectly normal, and used for various (social) purposes other than reproduction.
Why isn't everyone bi? might be a more interesting question. Why aren't we more like bonobos?
As regards those getting all wibbly over the use of 'normal' this is just a standard usage in science, and doesn't imply a value judgement. So, homosexuality isn't 'normal' in the statistical sense.
I tend to think people are born peopl(ish), and their full suite of interests and skills develops as they develop. There are genetic influences, of course there are, but our personalities are complicated, emergent structures, rather than the simple this gene means blue eyes, this gene means they'll be gay of the simplistic 'nature or nurture' pseudo-debate. After all, we are genetically products of a very different environment from the one that we spent most of our evolutionary time in -- yet we are very successful in terms of longevity and in terms of sheer numbers. Sex, and possible sexuality and sexual responses and social and biological uses of sex is wider than the simple 'sex is for reproduction' of those who get stuck at the 'homosexuality is unnatural' stage - which as we now know just isn't true in terms of other species anyway!
Homosexuality is 'unnatural', but then so is almost everything else that humanity gets up to in between eating, sleeping, and fucking to make babies!