[@Pair of Hearts]
With most of my characters I usually have an element that's hidden away from the character sheet; something from their past or a future event. If you look at my writing I'll start to incorporate these aspects and slowly expose them, leaving others to make the call if they want more.

Most of the time I think it's the GMs that govern this when they present any character sheets themselves. They go into details and history for their characters and ask for players to do the same in their [b][i]bio[/i][/b] sections. Half the time what is written is never used in the roleplay itself.

Worse part is I now naturally write about a character's life events in a character sheet because I've been trained to do so.