I suppose you could say homosexuality is "abnormal". But it's still natural, since it happens in NATURE with animals. Dogs, cats, monkeys, ect.. But answer this.
Would you rather have two gay parents raising up a child who else would be in a shoddy orphanage, or two still gay(no matter what..they will be gay. Just like you cant turn gay, they cant turn hetero) people in a marriage with people they dont truly love, and thusly have big arguments with each other, affecting the children's psyche, creating even more screwed up children in a world full of them.
Besides, the homosexuals can always get a surrogate mother. Thus getting a child if they wanted to.