Michael -- marriage is not about granting your son any right to happiness. He is free to pursue his own happiness and I wish him well in doing that.
Marriage is not personal. It is a social institution. It needs a public document. It is done in a public ceremony that confers public recognition. This is done because traditional marriage between a man and a woman benefits society in many ways. If it is on the wane among heterosexuals, it is because it is a burden and an obligation as well as a joy (to the fortunate). Gay marriage, on the other hand, is about nothing but a cynical attempt to grab government benefits.
If you are homosexual, I have no problem with that. Be happy and prosperous. But leave the public out of it.