His bicep insertions are naurally quite high in both feel and kid pics
....but very low now..?
Nah man, in the second pic (younger) he is flexing them differently. Look at the wrist. Your bicep looks shorter when you perform a regular db curl than when you do a hammer curl. The same applies here (same difference in how you flex your bi), but you're a way more experienced dude than me, I'm sure you know this already