Most people assume that she was the daughter of Iset Nofret I, second Great Royal Wife of Ramses II and this is the theory I subscribe to. Some would say that she could still be the daughter of Nefertari but it would be unlikely that any chile of Nefertari and Ramses would be given the same name as the next most important queen after Nefertari. Others would say that she could be the daughter of another queen but this is unlikely for two reasons: i) In the first few years of his reign Nefertari and ISet Nofret I are the only queens who appeared to have bore his children.
ii) Iset Nofret II was given a place of honour beside the legs of Ramses II on the facade of the Great Temple of Abu Simbel along with the others children of Nefertari and Isetnofret I. Only the children of the first two great queens were honoured here so if Iset Nofret II was the child of a minor queen she would not appear here.
There are parallels here between Nefertari II, also on the Abu Simbel Facade, and Iset Nofret II. Even the little daughter of Bintanath, whose name we do not know for certain, apears to have been named Bintanath after her mother.