If there's anything that humans have been selected for for over a million years, it's how to become a functional adult when one is raised by mediocre parents. Obviously, you want to try to do your best, but don't sweat it too much.

In contemporary middle-class American culture, parenting is seen as an awesome responsibility, an unforgiving vigil to keep the helpless infant from falling behind in the great race of life. [... This is] part of the same mentality that sends yuppies to "learning centers" to buy little mittens with bull's-eyes to help their babies find their hands sooner. -- Steven Pinker, "The Language Instinct"