Parents often don't realize what their children don't see on television affects them just as much as what they do. They often don't notice the more subtle forms of brain washing performed on their children by their teachers and peers.
Some effects are obvious.
This is a very obvious effect television has on some children, but it isn't across the board. Which brings me to a much larger issue. Growing up, I had some pretty skewed perceptions of white people. I lived in a nearly all black suburb, all my friends were black, everyone in my family was black, I went to a black church, and I attended a black school with white instructors. Therefore, my only interaction with white people came from television.