The Circle of Life

I was looking through images on the Library of Congress site and came across a photo of a woman who looked remarkably like my mother. She was President Chester Arthur's wife, Ellen Lewis Herndon Arthur, or "Nell". Herndon and Lewis are family names, so I did a little digging. You'll be surprised, but of course, she was part of the family. In the same vein, I found a photograph of my great grandfather who looked remarkably like me at the same age. If these people had such similar genes responsible for our appearance, how much of our behavior is tied to them? Does that mean I'm crazy because Meriwether Lewis was?