The immediate family is a young child's most important influence. Probably school, and then television.
Many children watch three to five hours a day, and that is too much.
For one thing, many studies have shown that watching TV violence makes some children more aggressive. Commercials aimed at children encourage them to eat sugary snacks, and that can lead to obesity. The time spent watching TV takes away from time spent doing other things. If necessary, you could install a lock box on your TV and make sure you provide your kids with plenty of other things to do while they make the transition to less viewing. This information is not a tool for self-diagnosis or a substitute for professional care.