SELECT Hometown FROM people WHERE Age  >  23 INTERSECT SELECT Hometown FROM people WHERE Age  <  20
Show the hometowns shared by people older than 23 and younger than 20.
[Schema (values) (types)]: | gymnast |  gymnast : gymnast_id (text) , floor_exercise_points (number) , pommel_horse_points (number) , rings_points (number) , vault_points (number) , parallel_bars_points (number) , horizontal_bar_points (number) , total_points (number) | people : people_id (text) , name (number) , age (number) , height (number) , hometown (number);