Tweenager
On average, girls begin puberty at ages 7 to 11; boys at ages 8 to 12. Girls usually complete puberty by ages 15 to 17, while boys usually complete puberty by ages 16  to 17. The major landmark of puberty for females is menarche, the onset of menstruation. This usually occurs between ages 12 and 13; for males, it is the first ejaculation, which occurs on average at age 15.In the 21st century, the average age at which children, especially girls, reach puberty is lower compared to the 19th century, when it was 15 for girls and 16 for boys. This can be due to  improved nutrition resulting in rapid body growth, increased weight and fat deposition or eating meat from animals which have been dosed up with estrogen.