i have a 12 yr old brother he going to be 13 in a month but all he wants to do is lift with me. he wants to be as big and strong as i am. i keep telling him that the chance of that is going to be low because we come from diffferent dads, mine 6'3" 225lbs his 5'8" and not very big he himself is about 5'4 90lbs is it ok to work him out at that age? or do u think i should wait? any adivse would be helpful