What with the current wave of religious fanaticism sweeping the country, and the concomitant attempts to put homosexuality back under wraps, the whole concept of a homosexual "lifestyle" has come back to the fore. Leaving aside the fact that the word "lifestyle" always puts me to mind of furniture catalogs and leisure suits, the idea that someone would choose to be homosexual (as opposed to being born that way) isn't reasonable and goes against common sense. To believe that someone would choose to be homosexual, you have to accept some basic premises:
So, in order for someone to engage in homosexual acts, they have to consciously disregard their natural heterosexual urges; engage in activity which by all rights should be physically repulsive to them; and engage in behavior which will alienate them from their friends, family, and society. They not only have to do something that feels unnatural, they have to disregard what feels natural. What could possibly cause someone to choose that kind of life?
If you think homosexuality is a choice, what would cause you to choose it? If you think you couldn't possibly become homosexual, remember that you got the same start in life as anybody, and lots of people chose it, despite monumental obstacles. Why didn't you choose it? Something convinced some people to suppress their natural urges and choose to be gay.
If these arguments sound silly, it's because they are. If homosexuality is a choice, then heterosexuality is also a choice. If you have that choice, then heterosexuality is merely the default setting you're born with, it isn't set in stone. (Does that mean any straight person could become gay if they chose to? Some people think so.)
Clearly, there's a spectrum of sexuality, and everybody falls somewhere in that spectrum (unless they're completely asexual). But the idea that you choose your sexuality seems rather unlikely to me. If it was a choice, then it seems reasonable to expect that the vast majority people would be closer to the middle of the spectrum rather than bunched at the ends.
Protesting the gay pride parade isn't a choice! It's a "lifestyle"!