Scientists say that the brain is fully developed and matured in the late teens or early 20's, depending on the individual. The average would be 21.
Just after puberty, this time is when the brain is 'metaphorically' rushing around trying to sort everything out before you get too old. After this has happened the brain has a hard time trying to...
The human skeleton usually grows until about 25 years of age.
The human brain is fully-developed at about age 20.