A friend of mine and his wife have an adopted child. They are her parents. However, while raising her they made efforts to involve her birth family whenever possible. So for Thanksgiving, her older brother and her grandmother were invited to their house. The birth mother was also invited but couldn't make it because she was in jail... my friend and his wife gave their daughter a loving, stable home.
At the same time, I think by fostering connections with her birth family, they have not cut her off from her roots.
I think it is important for adoptive parents to understand that their children's pain needs to be expressed and acknowledged. That it's not an insult to them, but a need that the child has.