Mulder and Scully head to the home of Kyle Gilligan where they talk to his mother in episode 10x02 "Founder's Mutation".
Source: IMDb
The trio heads to the home of Maddie's parents where Jules and Richard have lunch with her mother in episode 1x04 "Cohen, Lenny Cohen.". Maddie recounts the very first con she pulled as a teenager in episode 1x10 "Always Forward, Never Back".