what they did wrong.  Most likely the correct answer is they did nothing wrong.  We all have our agency to chose and even if in word you didn't 'teach them something' you most likely did in deed.  The only parents who are failures are the ones who don't care.  Since you obviously do care then you are a success and maybe you are a parent to your son because you could handle it and because you could support him in a productive way.  If God isn't dwelling on your past then neither should you.  Have courage there are a lot of surprising people who are there to help you.