If you're a parent faced with the impossible task of trying to plan your kid's life to give it stability in an intrinsically unstable world, look no further: finding a good jiu-jitsu teacher will fix and prevent all sorts of serious problems.
But don't take my anonymous word for it. Below is Rickson Gracie's explanation for this phenomenon, taken from a recent interview.
"In terms of experience, a kid who gets into a school at seven years old, he may stay for life in the school, or at least for three, or four, or five years, until twelve or thirteen. So in this period, he's in contact with the same instructor, dealing with the same problems, which is bigger than any other instructor or any other teacher he's gonna have in his school life.
"Every year in his school life, he changes instructors, he changes disciplines... But in a jiu-jitsu school, he can stay with the same presence, with the same instructor for maybe his entire teenage years; and that plays an important role, because you start to develop trust in your teacher, and admiration for your teacher, and a friendship, and a situation that can escalate to the point where he's gonna be guided by the example.
"So jiu-jitsu has not only the perfect attributes to be connected with the student, but also, a jiu-jitsu instructor has the time needed to really work on the character and the personality of the student. So it's an amazing thing, the difference between the kids who are involved with jiu-jitsu and the kids who are not involved. It's amazing in terms of self-control, in terms of perception, in terms of being a good person and being able to share more love instead of being insecure and violent. So the benefits are huge, and I recommend it to every father."