To be honest, I think there may be even more pain and mistrust from a deadbeat parent. Adopted kids get a clean break with a new family. However the child of a deadbeat parent gets intermittent reminders that they are there, but won't take the actions required to care for their child.
Not to say adoption is easy, but make no mistake -- having a biological child is no guarantee that the parent will have zero trust issues with said child, especially if divorce or abuse become involved.
Not to say adoption is easy, but make no mistake -- having a biological child is no guarantee that the parent will have zero trust issues with said child, especially if divorce or abuse become involved.