mips

Hi folks, I am interested in having my son (5 years old) start martial arts, at least to see if he likes it or not. Not sure what a good style would be for him to begin with so looking for suggestions. He does gymnastics so he is very agile and acrobatic. I've studied myself from ages 13-24 earning a 2nd dan in aikido and jujitsu before blowing out my knee and having to quit. I don't ever remember seeing children in my school near his age so I am not sure if those styles are right for him.