At 18, he's around 6'2" tall and weighs 156 as of last week.
He was born skinny at 21 inches (even) and 7 pounds (even).
When he was four and went for his annual physical, he was in the upper percentiles for height and lower for weight. The next year, at age five, he grew about 4 inches and his weight was identical to the year before.
He's tried weight supplements, protein shakes, high calorie snacks, etc. but has never broken 160 pounds.
This is the first year he has been involved in a formal weights program beginning with the fall semester in college so it's too early to tell if that will help with the whole body mass thing. (it hasn't so far
But you work on the things you can control and the rest will fall into place.
(And Krak, he's a guitar player, too, so our boys have that in common as well
