Is there any study for this?

I had a thought recently wondering if there were any polls or studies asking orphans of a decent age (maybe 12 or older, at least old enough to understand the issue) if they would mind having adoptive parents and if it would affect who they would allow to adopt them. It doesn't seem like the children themselves get to have much say in who can adopt them, which is really saddening. They only allow parents who they think are capable and are safe to be given the duty as parents, so why reject an entire group (the GLBT community) instead of looking at them in an individual scale first?