It's the usual story: "martial arts is violent so it's a bad influence on kids". Some people go as far as suggesting that martial arts should be banned altogether, but luckily those people are few in number. But does martial arts actually promote or even encourage violence?
Generalising to suggest that every aspect of martial arts does so is misleading. There is a big difference in the way martial arts is portrayed on television and how it's taught in a dojo.
Martial arts films are created to be entertaining so they're often overly violent. No wonder people are concerned that the actions performed on television will be seen by kids and then repeated on the playground. But then again, violence is everywhere and out of all the stuff they could be exposed to, martial arts is pretty tame.
As with many things in life, education is the answer. Provided kids go to an ethical martial arts school, they will learn that martial arts is taught for self defence. I know several schools that would throw out students who use martial arts to bully others. In my opinion that is the way it should be.
I find that if kids learn martial arts then they tend to become less violent.
The majority of kids who train in martial arts are on the whole not violent and after a period of training they almost never become violent. Of course there are exceptions, but on the whole they don't. These kids sometimes start off quite timid but after a few lessons they begin to build some confidence. You then have a minority of kids who do get violent. They're often cocky and think they know it all. In my experience one of two things happen to them. Either:
As a final note I will mention that Wado Ryu, a style of karate, translated into English means "the way of peace and harmony".