When Young People Grow
"The year of greatest growth for boys is the seventeenth; in girls the fourteenth. While girls reach full height in their fifteenth year, they acquire full weight at the age of twenty. Boys are stronger than girls from birth to the eleventh year, then girls become superior physically to the seventeenth year, when the tables are again turned and remain so. From November to April, children grow very little and gain no weight; from April to July they gain in height but lose in weight; and from July to November they increase greatly in weight but not in height. A doctor having studied the subject, says the growth of children takes place entirely when they are asleep."
I bet you didn't know that.