Impetuous and moody, teenagers will often storm off in a sulk if they can't have it all their own way.
Now science has found an explanation for the impulsiveness that causes so much friction with parents - the adolescent brain hasn't yet developed patience.
Researchers found that teenagers base many of their actions on immediate gratification, thinking more about the here and now than the future.
They do not learn how to control their impulses until nerve connections increase in the part of the brain that deals with decision making, German researchers discovered.
In a study, 50 people aged between eight and 25 were asked if they would rather have smaller payments now or larger payments later.