Atheists, since homosexuality is legal in America, will there be another baby boom?

I don't see the correlation. The first baby boom was caused by all the male soldiers returning home after WW2 and promptly starting families. We don't have a war on that scale keeping men from their loved ones.

There might be a lot more adoptions occurring, every child should have the chance to live in a happy family regardless of the number of mothers or fathers.

Only if two men or two women impregnated each other. That's a rather difficult task, for obvious reasons.

This question reveals an appalling lack of sense

Homosexuals don't have children. I don't see a tie-in.

The sidewalks might be damp in the morning, too. Many unrelated things happen all the time.

Logic isn't your long suit, is it?

no