Or even great-grandaughter, if we go with "Obi-Wan sired a child during his time on Mandalore as a Padawan with Satine Kryze - but she kept that child's existence secret".While she might be Kenobi's daughter she looks too young for that. Age would fit grand daughter better.
According to the Visual Dictionary Rey is 19 as of TFA, and TFA is 30 years after RoTJ (so 34 years after ANH).
Timeline fits. But I've never read any of the books or stories for the EU so I never considered it.
Evidently Padawans are randy devils.