The time of puberty varies from child to child, but usually begins around 10 or 11 years old. Girls typically begin the process of puberty at age 10 or 11, and boys at age 11 or 12. Girls generally complete puberty by 15–17, and boys by age 16 or 17. Nutrition, genetics and environment also usually play a part in the onset of puberty. Girls will go through a growth spurt and gain weight in several areas of their body. This is due to the natural processes of puberty, but genetics also plays a part in how much weight they gain or how much taller they get.