I say no to both.

I disagree with the concept of marriage as a concept at a fundamental level and believe it has spawned a broken society (I am a polyamorist and an atheist/agnostic).

I don't say no to gay adoption as such, but since adoption is based on a percieved need for parents, based on the institution of marriage, I disagree with it fundamentally also.

I also believe morals and ethics are subjective, and that "natural rights," being a product of these, but with a presumption that they are otherwise, are total horse excrement.