She was the daughter and known child born to Ptolemy II of Telmessos by a mother whose name is unknown.
[4][5] Through her paternal great-grandfather Ptolemy I Epigone, she was a direct descendant of Lysimachus who was one of the Diadochi of the Greek King Alexander the Great who was King of Thrace, Asia Minor and Macedonia[6] and the Ptolemaic Greek Princess who was Queen of the Ptolemaic Kingdom of Ancient Egypt Arsinoe II.
[7] Through Arsinoe II, Berenice was a direct descendant of Cassander, the brother of the powerful Regent Antipater.
[23] According to an intact stone inscription found in Nahavand Iran dated in 193 BC, Berenice's father is described as a relative of Antiochus III.
[24] This reflects his court title and in fact, Ptolemy II and Antiochus III are distantly related.
The first letter is from Antiochus III addressed to the Strategos of the Carian Satrapy and is the above-mentioned stone inscription from Nahavand, Iran: The second letter is addressed to the Hyparch of the district from the Strategos of the Carian satrapy: After her chief-priestess appointment, not much more is known on Berenice.