The OP was about abortion, that topic always seems to make me think about freakonomics lately.
There are a bunch of people who have the traits necessary to be good parents with bad genetics and vice versa. I think that the next evolution of humanity (necessary for the species survival) needs to take thought like this into consideration.
But I understand why you object.
I'll leave you with this, think about the worst hereditary afflictions that exist, they could all be eliminated.