Young boys have a lot more options than they once did. They are able to get crew cuts and make their hair nice and spiky. A lot of this is due to many great hair products coming onto the market. It is a lot easier to get a boys hair to stand up then it used to be.
It is best, though, to get a simple style for kids. This makes it easier to style their hair in the morning. Most parents do want to spend hours doing their children's hair. The more simple the better, really. When kids are old enough to do their own hair then they should get more complicated styles if they wish to.
