What is the average age Puberty begins

   At about the age of twelve in girls and thirteen in boys, puberty or adolescence starts. The child is rapidly growing to be an adult. Among some people and in some religious groups, there are ceremonies to honor this new stage of human growth.
   The word puberty is from the Latin pubes, meaning citizen. Today the word is narrowed to refer to the young person's beginning sexual and social maturity.
   With the onset of puberty, bodily changes called secondary sexual characteristics gradually appear. In both boys and girls the sexual organs start maturing; sweat glands become more active; and hair commences to grow in the axillary regions (armpits) and pubic regions.
   In boys the voluntary muscles develop more than in girls, and the shoulder bones broaden. The boy's voice deepens—often "cracking," and hair gradually grows on his chin and cheeks.
   In girls starting puberty, the pelvic bones grow broader, the breasts start maturing, and an even layer of fat tissue forms and rounds the outlines of the body. The teenage girl's voice enriches to the feminine ranges from contralto to high soprano. The monthly cycle of menstruation also starts. Accompanying these bodily changes are complex changes in the emotional sensitivities of adolescent boys and girls. Changes of mental outlook vary from those of a new excitement about the world and a heightened appreciation of human beings to spells of independence and severe criticism of that world. Adolescents are helped through the changes of puberty by the good example and guidance of parents and other strong adult leaders whom they can admire.