Teenage bodies undergo dramatic changes, though the rate at which adolescents mature varies markedly from person to person. Many boys grow three to four inches in a year, for example, while some grow twice that amount. It is both realistic and reassuring to think of a range when assessing what is a “normal” indicator of a teenager’s development—from the onset of adult sexual characteristics to the sudden appearance of skin blemishes (acne).
The following milestones are based on averages and general recommendations; they should be viewed as a guide rather than a rigid standard.