I respectfully disagree with you JStalin, but agree with you on one point - gay marriage will not make anyone gay. I should have been more specific. It could be said that gay couples deprive society of future children because of their lifestyle.
Gay marriage will affect the population growth.
For example, let's assume that there are 10,000,000 gay men in the United States.
If they always remain gay, they are incapable of having their own children, without a female.
Let's look at three scenarios.
1) A gay couple, never have children and never adopt. They die, their family line dies with them. Because they are gay and remain childless, they have unwittingly deprived themselves and society for the potential of future children.
2) A gay couple adopts a child, but when the gay couple dies, the biological line dies with them.
3) A gay couple decide they want a child, so one gay man uses a surrogate mother. Mother gives birth, gay dad becomes legal parent of child, but his partner remains childless (unless he adopts). Direct biological line will survive with gay dad, but his partner will die childless, and his line will end.
Gay marriage will not necessarily result in a lower birth rate, there are other statistics too consider. For example, women who put off marriage and children to pursue a career, may find they don't have time to have children. The secualrization and leisure lifestyle may convince some women they don't need or want a child. It's true that abortion also lowers the birth rate.The combined factors do result in lower birth rates. I encourage you to read "Death of the West", the author knows what he is talking about.