Its my experience that girls tend to be terrifically smart until they grow breasts. You may dismiss this observation as my personal prejudice, based on my own tender age, but thirteen years seems to be when human beings reach their fullest flower of intelligence, personality, and pluck. Both girls and boys... Let girls get their menstruation or boys have their first wet dream, and they instantly forget their own brilliance and talent... Girls get their boobs and forget they were ever so gutsy and smart. Boys, too, can display their own brand of clever and funny behaviour, but let them get that first erection and they go complete moron for the next 60 years. For both genders, adolescence occurs as a kind of Ice Age of Dumbness.