Not being self-critical does not mean things don't happen. Suppose you love drinking, for example. At 20 it will be just a hangover, but at 40 it could even kill you. If at 40 you get drunk knowing you no longer process alcohol like you used to, that's a flaw of character. It doesn't have anything to do with DNA(supposing you're not an alcoholic). Mistakes have much more weight the older one gets. It's a fact, not a way of seeing things.