Could it be the hormones and the steroids in the food we eat that are making teenage giants.
Most of the high school age boys I drive on my bus are enormous.
Last Wed I drove a baseball team and found out on the way home after the game they were middle school age. One of them was 6ft 6 ins.

and not a beanpole.
At 5 10 when I walk down the corridor of the high school I feel like a dwarf.
Same here, 5'10" and what I think is normal height or pretty close to it, although 280lbs. is not so normal.....

Yah, high school kids are taller and overall bigger than when we were kids for sure, what is causing it I do not know. My kid is only 5'9", 165lbs. and small hands and small feet (size 9-10 is all) but a lot of kids in his class make me look tiny both weight and more so height wise.
At the lifting meet, the heavyweights are HUGE never knew so many kids can be over 285lbs. and still not look massive due to their 6'4" or more height. Almost all the lifters in his 165lb. weight class are pretty short though say 5'6 is all and stockier/shorter arms-legs, and that also helps in weightlifting to lift more weight, in general.
What really surprised me is the females and how many females are into lifting weights. Some 160-165 lb. girls I saw were doing NO JOKE 320lbs. in squats as a final lift which puts most high school boys to shame similar weight. I know for a fact right now without lifting weights for decades that 300lb. squat would not be do-able without pulling a butt or leg muscle or maybe blowing a knee out. A local heavy hitter powerlifting team 100 miles or so away has more females in their team lifting sport than males which surprised me.