My mother told me about this piece of Mexican birthday folklore from her family. Her father is from Mexico (Zacatecas specifically), and her mother is Caucasian, so she learned this tradition from her father (who learned it from his parents) This folklore is very important to my mother, because it’s a connection to her father’s heritage and is also a fun family tradition.
Every birthday, the birthday person is woken up by the other family members in the household by playing the song “Las Mananitas” (the morning song) The family members start the music while entering the birthday person’s room with a bed tray of Mexican sweet bread (pan dulce), Mexican hot chocolate, and presents. The pan dulce can be purchased from a local bakery (panaderia) or made at home, although the process of making it can take a long time, because the bread dough has to rise twice. So, having homemade pan dulce was always a very special occasion.
Because this only takes place within the family, it has become one way to indicate who belongs in the family. For example, after my cousin got married to her husband, when it was his birthday, my cousin’s family came into his room playing the song and holding pan dulce. It was surprising to him, but it was also an unofficial way of welcoming him into the family.