I found this blog post very interesting and relevant to the topic: Do You Have a Right to Know Your Father? | Clarissa's Blog:
Understanding who your parents, grandparents, and great-grandparents are is crucial to one’s identity. People who falsify another person’s history because they find it more convenient to themselves horrify me. One can have a gazillion spouses, lovers, casual sex partners. But there is only one set of biological parents one can ever have. They might be horrible people, one might make a choice not to have any contact with them, but that’s a decision that belongs to each person. Nobody is entitled to making it for other people.
I think people need to remember that their children are not toys. They are not objects whose only purpose is to serve the parents’ needs. They are human beings in their own right. Denying them the basic truths about themselves for whatever reason is completely wrong.
Adoptive parents, foster parents and surrogate parents are part of a person's personal history, and part of their family history. They obviously had an influence on that person's life, for good or ill, as did friends, teachers, bosses and other people one comes into contact with. They are efen part of the family history. But they are not part of the person's genealogy. Genealogy is about where you get your genes from.