Rosa Esther is een dochter van Gerrit Polak en Esther Seemer (A'dam, 17 april 1883 - A'dam, 17 maart 1937). Haar moeder overleed toen Rosa 16 jaar oud was.
In addition, a Jokos file (number 52753) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.The Jokos file reveals that a claim was lodged for compensation for valuables surrendered to the Lippmann-Rosenthal looting bank (L-claim, number 1).