The sexual orientation of your parents (and what they do in the privacy of their bedroom) is not something you want to think about...so why should it matter when it comes to adoption? As long as the child is being placed in a loving, stable home with the financial resources to raise that child, it should not matter if it's Mom and Dad, or Dad and Dad, or Mom and Mom...or whatever. Love is what matters and in this cold, cold world there is such a shortage of genuine love that we should not try to refuse any possibility of it. Even those who say we shouldn't let gays adopt have to agree that a single parent home can be a real hardship and adversely affect a child...two parents has to be better, if only because they can share the joyous task of raising a child. I have been a single mom and I know that it can be done and still have good kids but trust me, it would have been easier on me to have been able to share that load even as I carried it willingly. And why should we keep a child in an orphanage when there are couples who want, even yearn to give this child a home? Who are we to say that they are bad parents, would be a bad influence? What proof is there that being gay and adopting means that you'll "turn" the child gay? None, by the way. And if your child ihappens to be gay, what better place to be than in a family where the parents understand the issues facing the GLBT community in a deeply personal way.
Frankly, way too many people are astoundingly nosy about what other people are doing in their bedrooms...and it has nothing to do with how good a parent they would be. Look at all the heterosexual couples who have children that are abused, neglected, mistreated and generally have miserable lives. Adoption agencies, and the civil regulations/laws/policies about adoption, should be based on what is best for the child. Not on some quasi-righteous platform of who is holier than who, or who has the "right" skin color, ethnic origin, or sexual orientation--none of that has anything to do with the simple act of love, of caring for another human being, of becoming a family.
Love has no boundaries and we need to stop trying to create them.