My xinyi and taiji teachers both told me that these styles shouldn't be taught to kids younger than 13~14 and if I remember correctly they said it was because they cause the body to contract and the tendons to get longer, therefore they would stunt the growth in children. My xinyi/chaquan teacher told me that I could only teach an external art like chaquan to children. So how true do you think these claims are and do you think that it's necessary to wait until they are about 13? The reason I'm asking is because a few people have asked me to teach their young children taiji and I'm not really sure if I should.