According to an interview that Rob Morrow gave to 'The Jewish Journal of Greater Los Angeles', the Eppes family was not explicitly identified as Jewish until the fifth season, when Morrow asked the showrunners to make a point of it and to include a storyline in which his character, Don, starts to explore his religion (Morrow may have forgotten that in the season four episode "Robin Hood," Charlie does mention that he is Jewish). There were some implicit references to the family's Judaism earlier than that, however, including the comment in the very first episode about Alan serving brisket on Friday nights and Don and Charlie's conversation in the Season 3 episode "Provenance" about how it was weird that their mother had wanted a Christmas tree.