Sydney Anne DiMera is the biological daughter and second child of Sami Brady and EJ DiMera. Sydney was born in secret on January 28, 2009, while her mother was in the witness protection program, and she was switched shortly after birth with the daughter of a young teenage mother, Mia, who had agreed to give her baby up for adoption to Nicole Walker.
Nicole, who had miscarried fiancé EJ's daughter, had arranged in secret to adopt Mia's baby and pass the child off as EJ's, fearful that she would lose EJ without a baby. When Nicole learned that Sami had just recently given birth to her daughter as well, Nicole switched the babies, preferring to have EJ's daughter over an unrelated child.
Sami and EJ were none the wiser to Nicole's treachery, and Sami and Rafe bonded over "Sami's" daughter, while EJ and Nicole bonded over "their" daughter. After an extensive baby name search, EJ and Nicole decided to name their daughter Sydney on February 4, 2009.
On March 20, 2009 Stefano confirmed that Sydney's middle name is Anne. Now that both Stefano and Tony know that the child is not Nicole's. On October 2, 2009; EJ reveals that he knowns that Sydney's is not their child but thinks that It is Mia's child.
- Will Horton (biological maternal half-brother)
- Johnny DiMera (biological brother/legal paternal half-brother)
- Allie Horton (biological maternal half-sister)
- Unnamed Sister (biological paternal half-sister/legal sister; deceased)
- Grace Brady (biological maternal adoptive half-sister)
- Stefano DiMera (paternal grandfather)
- Susan Banks (paternal grandmother)
- Edmund Crumb (paternal step-grandfather)
- Paul Mendez (legal maternal grandfather, deceased)
- Fay Walker (legal maternal grandmother)
- Roman Brady (biological maternal grandfather)
- Marlena Evans (biological maternal grandmother)
- John Black (biological maternal step-grandfather)
Aunts and Uncles
- Alexandra "Lexie" Brooks (paternal half aunt)
- Benjamin "Benjy" Hawk (paternal half uncle, deceased)
- Anthony "Tony" DiMera (paternal legal half uncle, deceased)
- Megan Hathaway (paternal half aunt, deceased)
- Renee DuMonde (paternal half aunt, deceased)
- Brandon Walker (legal maternal half uncle)
- Taylor Raines (legal maternal aunt)
- Eric Roman Brady II (biological maternal uncle)
- Caroline "Carrie" Anna Brady (biological maternal half aunt)
- Rex Brady (biological maternal half uncle)
- Cassie Brady (biological maternal half aunt)
- Isabella "Belle" Black (biological maternal half aunt)
- Brady Victor Black (biological maternal step uncle)
- Donald "D.J." Jeremiah Craig (biological maternal half uncle)