What influences us most

For most of us, our earliest memories date back to around age five. It's possible that some people remember things from age three or four, but certainly no one remembers things from before that. We may think we can remember things from before that, but chances are what we remember are things that others have told us, and that we only think we remember. 

Talk to any psychiatrist, and they will tell you that character is formed mostly before that age. For instance, whether or not someone becomes a sociopath has mostly to do with whether or not he formed any real bonds with another human being before the age of one. This is why orphans who are adopted after the age of two, no matter how nice the family, often turn out to be sociopaths. 

It's a little strange to think that your entire character -- your loyalty, decency, honesty, self-control, capacity for love, capacity for work, and ability to take criticism -- is determined almost entirely by things you cannot remember.

But at a certain level, somehow, it makes sense.