Sociological and economic background.
This one has the potential to be a laundry list of detail. Grab a handful (if not all) the following questions, and see what you can come up with.
What was their childhood home like? Did they grow up wealthy or low income?
How big was their family? Are they close with everyone, a select few, or no one at all?
How involved were their parents? Was this by choice, or by circumstance (i.e. were they busy working, did they make time, etc.)?
Were they a good or bad student? Did they care? Why?
Does the character believe in marriage, and do their parents affect this view? Were they married or divorced in the character’s childhood?
Are they religious? If so, what religion? If not, why?
Are/were they involved in their community?
What were their hobbies?
Don’t forget to comment below with your answers!