Well let me try. After 1950, nobody what really changed the world but what is known is that people started to develop "Mutations" specially in Japan which seemed to be the ground zero of this event, At first as you would expect everyone was confused and scared of this event, but after every generation after this first one had even more people with super powers to the point that now in 2010 it is the weird to find someone without them (They still exist tho). Being a super hero has became something like any other job a fusion between Law enforcement/Emergency Work/Paramedic and a rock star, And by that it means it is government enforced (Nobody can just get a cape one day and say they are a super hero without being called a vigilante nowadays), And the best way to get that sweet goverment pass is a Super Hero highschool, where you will learn how to use your powers. Kind of a shitty Synopsys. Hope it catches your interest.