I have what I guess is a pretty un-nuanced, old-fashioned view of Don't Ask Don't Tell. Basically, the purpose of the military is to bring violence upon our enemies. It's not a tool of social policy. If having gays serve openly in the military enhances its ability to do violence, then I'm all for it. If not having them serve openly works better, then I'm all for that. If DADT is the best policy, then... well, you get the picture.
It's possible to take that "best for the military" thing too far, of course. I wouldn't support a policy of executing every tenth man in a platoon that screws up, even if that could be proved, via scientific study, to enhance military effectiveness. But our policy with regard to gays in the military has never been anything like that draconian. If discovered, they are discharged; that's all.
Being gay might be a personal choice, or it might be inherent. There's a big debate about this, and in some cases it might matter which is right. (Personally I suspect it's a bit of both, in different proportions for different people.) In the case of military policy, I don't see how it matters one bit. If it's a choice, then that's one choice that's denied to you, like wearing shorts and sandals on parade, or wearing a nosering and a mohawk. If it's inherent (which is a broader term than "genetic" - it might be inherent due to upbringing), then so are lots of other things that keep people from serving in the military. If you have flat feet, you cannot serve. Why? Because it detracts from military effectiveness.
Which of these policies actually is best for the military is not a question I am at all qualified to answer. But it should be the only question being asked. Whether it enhances social justice or something is irrelevant.