Laverne & Shirley (1976)

Season 4: Episode 15

Shirley finds it odd that she is small and brunette when everybody else in her family is tall and blonde, so she takes it on herself to find out if she's adopted or not. In the end, she get a speech from Laverne about ""does it really matter if you're adopted or not, when you're current family loves you"". Needless to say when Shirley opens the hospital medical records, she finds out that she's not adopted after all.