"I do love knitting patterns."

So, here in Washington State, we have our own little domestic partner bill going on. Basically, a gay couple can get every right married couples have. Death benefits, sick days to take care of their partner, all the like. The only thing they don't get, is the right to be legally married. This should be enough for conservatives, right? Apparently, not so.
Opposition has come, with petitions, and signs reading "Protect Marriage and Children"

And this is where I get confused.

Can anyone tell me how ANYONE could reach the logical conclusion that gay marriage is hurting our children? Anyone at all?

In fact, if anything, it helps them.
Orphans can be adopted by two loving parents. Right?

If anyone could give me a logical explanation, I would be grateful.