He is also at ~10% bodyfat while you are at 18-20%? Not that the fat makes THAT much of a difference at calves but it is a factor.
My calves are currently 40cm ( 15,75'' ) and i haven't worked them out for ~6 month.
Also i have girly bone structure , circumference above ankles is 22cm ( 8,5'' )
I am sure the fact i am mid ~195/17% adds up to them.
KF's calves is all cow! Calf-zilla!