I've had one of both---a super-chunk 18 lb 12-week old, and a skinny 18 lb 18-month old. They are/were both wonderful and healthy--active, and good eaters. They are both evening out right now somewhere in the middle of the bell curve. I don't think there's any particular reason that is easily identifiable in most cases. Mine were both breastfed on demand, and my chunky one was my only paci baby.
6/24/10 at 7:01pm