I almost understand inflicting a disability on a bad person. There are people to whom I'd almost dole out deafness, Down's Syndrome, blindness, autism, etc., that is how terrible they are as human beings. It would certainly make them easier to live with and cause them to damage less people than they do.
On their child, though?! On their newborn baby?! To cause pain and suffering to a newborn human being that will last their entire lifetime because of who his/her mother or father is?! Making a bad person suffer is one thing- but to make their child suffer as revenge on the parent? What about the suffering of the other siblings, the child's grandparents, the other extended family members, etc.?
I wouldn't do that even to Stalin or Pol Pot or Hitler's children, let alone to a jerk of the regular variety.