If your child does not have an open adoption with known birth parents or if you have lost touch with the birth family, there may come a day when your child expresses interest in searching for them and reuniting. First and foremost, remember that this is not necessarily a rejection of you. This is not in response to something you did not provide.
We all have an innate need to know who we are and where we came from. Your child's birth family is part of who he is and where he came from. Different children feel differently about this, and supporting his desire will show your child that you support him. Granted, this may be hard to do, but remember, your child will only benefit from learning more about his birth family's health and medical history, as well as any other genetic information he can gather.
Elly's adoption was closed. At 22, she was newly married and eager to start a family but, as she'd experienced all her life, she had to complete the doctor's forms with "unknown" in every box asking about her family's health history. She had contacted her adoption agency and indicated that she would be open to reuniting with her birth mother, but the agency had never heard from the birth mother. Searching was an option, but Elly just didn't know if she wanted to take it that far.
When Elly was six months pregnant, she got a call out of the blue from the adoption agency, informing her that her birth mother had contacted them and was interested in speaking with Elly. Later that evening, they spoke on the phone for the first time, her birth mother eagerly answering endless medical questions that Elly could share with her doctor.
Sharon, Elly's adopted mother, took the news a bit differently. Suddenly she had visions of this "stranger" being there when Elly delivered, trying to play grandmother, and only "showing up" when all the work was done. Through tears and prayer, Elly and Sharon came to understand each other's positions, and were able to embrace each other's need for reassurance that their bond would always come first.
Encourage your child to include you in her search should she ever pursue it. Embracing the need for a history and a heritage will strengthen the relationship the two of you have and convey that adoption is, indeed, a miraculous gift.
Assure your child that your love and commitment is unconditional — no matter how the birth family responds to her contact with them. If she encounters rejection, she will need your relationship more than ever. You can encourage her to separate negativity and the issues of the birth parent from her own self as a person, but mostly you can pray and grieve with her over another rejection and loss.
Before that day comes, instill in your child her value as a unique individual, created by God in the womb of another, but capable and responsible before Him as is each human being.