Personal story. At my bar mitzvah, age 13, the picture with my 16 year old brother showed a little squirt that barely came up to len's nipples.
At 15, coming home from summer camp, i got a horrendous case of mono
(thanks, phoebe) that put me in bed for months, relapsed at xmas, put me in bed for another 2 months. I went to bed 5'2" and got up at 5'8"! by age 18, i was 5'11". Life is strange.