On a really detailed character bio you can add in where a character was born or grew up. A lot of times this can make a HUGE difference to a character's personality and their history. Consider a character that lived out in the country and then moves in to the city. Or a character that was born in a laboratory and spent their childhood there, only to end up escaping later. How often do you consider hometown or birthplace when designing a character? What are some examples of your characters where it made a big difference?