“Should children be allowed to learn Martial Arts?”
The answer is: YES. Not only should they be allowed, but they should be encouraged to do so. Martial Arts for Children can be beneficial in many ways, both physically and mentally. The child will develop increased strength and agility, and also have better confidence in himself as a result of Martial Arts. What worries parents the most is that their child might become aggressive, or get hurt in training. The reality is that this is mostly a stereotype, and most children that become aggressive by practicing martial arts probably have other problems that would have caused them to become aggressive anyway. As for getting hurt in training, this risk is there (like in any sport), but when training in the dojo protective equipment is used that makes it difficult to get hurt.
There are many Martial Arts that a child can start, including Muay Thai. Here is a video of a very impressive young Muay Thai fighter.
Another good benefit that comes from Martial Arts for Children is that the child will be able to call on his abilities if it is required. In today’s dangerous world, this is very useful. However, this should be taken with a grain of salt. Just because your child knows Martial Arts, it doesn’t mean that he can defend himself in any situation or that he is somehow “safe”. Imagine a child going up against a full grown man. It is true that skill can make up for difference in size, but the child would need supernatural abilities to be able to win in such a situation.

With everything taken into consideration, enrolling your child into a Martial Arts for Children school definitely has more advantages than disadvantages, and can change your child’s life for the better.