Without peeking at a dictionary or consulting a learned friend, I'm going to guess that disowning a child is different than giving a child up for adoption. The latter can be done reasonably, I think, when a parent realizes she is severely limited in the ability to provide safety and care to her child. The former, disowning, seems to mean a cut-off of relationship. We may wish to do that in times of stress, fatigue or fear. But a child is always and forever your child.
That said, I have trouble with our Western notions of owning children in the first place. We are inextricably connected, called to steward them, teach, nourish and guard them. But owning them? Nah. Too capitalist sounding for me.
Because in the end the calling of a parent is to give the child away to the child's own dreams and adventures. We love them and hopefully give them solid ground for their formative years but then they are meant to go. To be sent. Perhaps not geographically. Maybe they keep living down the hall. But we parents do not own or control the futures of our children. This is both a great blessing and a terribly hard thing to learn.