It's called responsible parenting. Whether it's 1, 2 or 50 parents raising a child. Sometimes something goes wrong and no one is to blame except for the person committing the crime.
Single parenting is hard. I think most of us are doing the best we can. For the most part we have well behaved, law abiding children, but oh Holy Lord, let one dumb ass commit a crime and let said dumbass be raised by a single parent and all of a sudden it's because of that and not the criminal that is to blame.