I'm against it. It has an effect on children. It's abnormal. The arguments for it, such as any 2 people in love should be able to marry can be used to support incest
too. Letting them adopt children is disgusting to me, and that is another problem which people are forgetting or ignoring.
It's not set in stone that every child should be raised by a man and a woman. Many a time one or both parents die. Moreover, there are plenty of straight couples that are really not fit to raise their own children. Just because you feel icky, doesn't mean it should be unlawful.