Worst parent nominee: Beat up your friend's kid

I don't want to type the details of her horrendous abuse of a "friend's" child, because she didn't like his mom, but it's as bad as you've heard of. If  you read this regularly, you know I'm a serious liberal. That said, this lady should have her tubes tied as part of her long, long sentence. Maybe tied around her neck.

So what can we really do about people like this, besides put them in jail when we discover them, leaving their other kids without parents. (In this case, she abused her friend's kid but not her own, at least not to the same extent.)

But I'm more interested in stopping it from happening. The problem is I'm afraid the kinds of things I imagine might work would be too intrusive on the part of the government for me. I mean, suppose we found a gene allele that was instrumental in this kind of abuse, and we found a gene therapy (or cognitive therapy, or drugs) that could ameliorate it. Would we be justified in forcing the therapy on anyone with that allele, even if they had shown no tendencies toward abuse?

 If we did find a way to prevent people from hitting their kids, we'd have to:

• Sequence everybody's genome to find out who had the bad allelle (and the bad sets of alleles for other mental disorders besides being mean).
• Decide what psychotherapy or gene therapy or drug to use.
• Set up an organizational structure for forcing them to take it.
• Keep the government from abusing its power or from just screwing up.

 None of these would be easy, but I imagine Republicans in congress trying to "cure" homosexuality, or atheism, or liberalism when they get back in power. I think I'd rather put  up with some child abuse to avoid that.