Those that claim they had nothing to do with how their kid turned out often really had nothing to do with them as they were growing up. Many are physically present but emotionally 'checked out' from the whole parent role.
Hey Arch... do you have kids? Just curious. (The rant below is NOT directed at Arch, before I get flamed)
My daughter got pregnant at 16 (long story...do a search, it's on here). Now my wife and I have full guardianship, and are raising our grandson. The daughter is off doing her own thing supposedly trying to get her shit together after her little adventure with a gang, some police involvement, and some other shit I won't get into.
We have had her/us in counseling off/on since she was 13, and have spent a great deal of money/time towards getting her straightened up before she ever got pregnant. She was fine until about 12 years old, and then it just went down hill.
We sat and wondered what we did, and blamed ourselves for a lot of shit that wasn't really our doing. It boils down to who she was hanging around with that she kept secret because she knew we wouldn't approve. If you think you can know everything that they're doing, you fooling yourself. They and their friends learn how to hide shit really well, and by the time you do find out it's already too late, and you're just doing damage control.
Sorry for the rant, but these girls just don't have a fuckin clue what they're in for. It's all a big game to them, and think it will be fun. It's fun until they actually have to be responsible for the welfare of another human being's life, then it falls back to the grand parents because they can't handle it. You see more and more grand parents raising kids these days, and it's bullshit.