Some 10-13 year old boys want to start fighting full contact. In our club (Thai Boxing and MMA) full contact to the head starts with 16 and to the body with 14. I think, when the boys want to fight with full contact and the parents agree, there is no reason not to allow it. And for self defense it would be better. In my opinion boys until 16 years should use headgear in thaiboxing. In MMA punches to the head should start with 16 at competitions and only light contact in training to the head, because headgear is very annoying on the ground. I once watched a fight with two 12 year old kids. One fighter took some hard low kicks and punches to the gut. Then he stood groggy in the ring corner, after several punches and an elbow to the head. He tighened his sixpack and his opponed kicked him 8 times with full force in the stomach. He went down, but he was back on his feet in time. His opponent punched him to the head, clinched him and rammed one knee after another in his stomach, until the boy went down again and couldn't get up. When he hit the ground, his opponend kicked him in the belly - I don't know if that is allowed in Thailand. Pretty hard fight, but no injury and the kid smiled after a while. By the way, the boys in Australia seem to be pretty tough, too.