Why not their daughter.I thought that because when XLocke explained to Sawyer...
"42 - KWON" (Locke states that he doesn't know "if it's for Sun or Jin"), and "4-LOCKE," explaining that all of them had been touched by Jacob at some point in their lives before coming to the Island.
We saw Jacob touching both Sun and Jin on their wedding day. This implied that he had manipulated them....we never saw him "manipulate" their daughter. So, to me, it must be either Sun or Jin, or perhaps even both, as they were both touched.