Conversation so far:
Where was Ben Carson born?
Carson was born in Detroit, Michigan.
Did he have any siblings?
Carson's older brother, Curtis, was born in 1949, when his mother was 20.
How did Carson do in middle school?
When they returned to Detroit public schools, Carson and his brother's academic performance initially lagged far behind their new classmates.

Question: Where did they return from?
Self-contained rewrite: Where did Ben Carson and Curtis return from?