Arthur Fonzarelli was born to an Italian-American family. He and his mother were abandoned by his father. When the senior Fonzarelli disappeared, he left a locked box for his son, but not a key; the young Arthur did everything to open the box before finally repeatedly running over it with his tricycle, only to reveal that it just contained the key to the box. The only advice Fonzie remembered his father giving was "Don't go out in the rain in your socks." In the Season 6 episode "Christmas Time", a sailor delivers a Christmas present ostensibly from his father (played by Eddie Fontaine), who wishes to make amends. Fonzie is resentful, but at the end of the episode he opens his father's letter explaining why he left and reads it. He also learns that the sailor was his father, who admits in the letter that he doubted he would have the courage to reveal the truth to his son. In a later episode, Fonzie unexpectedly meets a woman he believes is his mother in a diner. She convinces him she is not, but in the end, she looks at a picture of Fonzie. In the final season, Fonzie meets his half-brother 'Arte' Fonzarelli, who informs him that their father is by-then deceased. Fonzie has mixed emotions upon hearing this, as this left so many questions about his past unanswered, but Fonzie bonded with Arte, who helped him cope. Grandma Nussbaum appears to have been a primary caregiver to Fonzie since the age of six. When he (instead of Grandma Nussbaum) moves into the Cunninghams' garage apartment—a plot development that helped precipitate his increased presence in the series—he turns his old apartment over to his grandmother. She is rarely referred to after that but she is featured in at least one later episode.