so it is okay for a brother to marry a brother?
This is what I've pointed out about your practice of dodging and not really answering. I give you an argument, rooted in equality before the law, and you reach for the most grotesque potential imaginable to attempt to taint by association what you cannot reasonably address else.
I've set out, factually, how the marriage contract needn't produce or concern itself with children. I have also set out how, were that to be considered, the homosexual couple could through adoption or surrogacy produce and provide for children. I've noted the argument against discriminatory practice. The only way you can object to homosexual marriage is by applying your religious dogma, the very thing you would and have objected to strongly when attempted by Islamic fundamentalists.