Keep in mind, Igyman, that almost all scientific advances are strictly amoral. It's how they are applied that demonstrates any morality on the part of the user. Human beings will always find a way to use technology for their own agendas. Genetic manipulation is no different. Scientific progress should proceed with a healthy cost benefit analysis approach.
BTW, slavery is still alive and well in places like Africa and the muslim world. Seems nonwhites are still enslaving nonwhites. Also, as far as the whole gay gene thing goes, the irony would be that if there is in fact a gay gene, that is exactly what many people will want to expunge from future children. So a gay gene could theoretically lead to fewer or no homosexuals. Once again, much depends on who would control such advances in science and technology in the future.