I agree with people over here.
I don't think it's genetic (so far, no "gay gene" has been foung, though it doesn't mean it won't be found).
Nevertheless I do believe it's biological/physiological (which it's not the same as genetic).
Hormones and how you develop in the womb, I believe it's the right answer.
That's why we ARE born this way...
It's said that certain parts of the brains "work" different in gay people (like the part that controls sexual attraction, obviously).
Just check this out. And get in Wikipedia "Biology and Sexual Orientation" for more info (I took only part of it from that webpage).
Biological differences in gay men and lesbians
Physiological
Some studies have found correlations between physiology of people and their sexuality. These studies provide evidence which they claim suggests that:
Gay men report, on an average, slightly longer and thicker penises than non-gay men.
Gay men and straight women have, on average, equally proportioned brain hemispheres. Lesbian women and straight men have, on average, slightly larger right brain hemispheres.
The VIP SCN nucleus of the hypothalamus is larger in men than in women, and larger in gay men than in heterosexual men.
The average size of the INAH-3 in the brains of gay men is approximately the same size as INAH 3 in women, which is significantly smaller, and the cells more densely packed, than in heterosexual men's brains.
The suprachiasmatic nucleus was found by Swaab and Hopffman to be larger in gay men than in non-gay men,[56] the suprachiasmatic nucleus is also known to be larger in men than in women.
The startle response (eyeblink following a loud sound) is similarly masculinized in lesbians and bisexual women.
Gay men and lesbians are significantly more likely to be left-handed or ambidextrous than non-gay men and women; Simon LeVay argues that because "[h]and preference is observable before birth... [t]he observation of increased non-right-handness in gay people is therefore consistent with the idea that sexual orientation is influenced by prenatal processes," perhaps heredity.
A study of 50 gay men found 23% had counterclockwise hair whorl, as opposed to 8% in the general population. This may correlate with left-handedness.
Gay men have increased ridge density in the fingerprints on their left thumbs and pinkies.
Length of limbs and hands of gay men is smaller compared to height than the general population, but only among white men.
Anyways... I hope this helps.
Again we are born this way ('cus I remember having sapphic feeling since I was very young, but I didn't recognize them as such) but biologically/physiologically speaking... not really genetically.