I was always the tall skinny kid growing up. At 18 I was about 6'2 and maybe 150-160 lbs. I ended up at 6'3 and well, a bit more weight. The wife is barely 5'0.
My oldest has always been pretty average size wise. At 16 he's 5'10, but has a chiseled physique I was never blessed with. I assume he will probably pick up a little more height, but end up no more than 6'0.
My youngest is a whole other story. He just turned 9 and is 56 inches tall, which is somewhere in the 90's for height percentile. He's also close to that percentage for weight despite the fact that he's actually skinny. I'm crossing my fingers he ends up with my height and his brother's build.