I don’t know why gay people choose gayness, but I chose to be straight the day I realized “Although I never ever ever want children, I just adore the added fillip and excitement that ‘risk of pregnancy’ adds to my sex life. And when I was single and dating — which is to say, spending time alone with people I didn’t necessarily know very well — I also loved that added risk of violent death vis-a-vis sexual dimorphism: if I’m with a woman who turns out to be a violent psycho hoping to kill me with her bare hands, there’s a pretty decent chance I could successfully defend myself against her. Which is booooriiiiiing. Gimme a psycho attacker who outweighs me by at least a hundred testosterone-enriched pounds! And my chances of getting AIDS and other STDs were always a lot higher from straight sex, too. With all the kickass advantages heterohood has to offer childfree women like me, it’s obvious that only a self-hating, risk-taking, masochistic fool of a woman would choose to be a lesbian instead.”
As proposals go, this one is fairly modest; but ’tis enough, ’twill serve.