The Force Awakens - Ren and Rei - My suppositions

Most of the internet chat I have read so far (and I haven't delved deeply) has suggested that Rei may be the daughter of Luke Skywalker.
This was not not my instinctive reading.While I accept Rei was attracted to Lukes lightsaber. I simply read that as a indication of her awakening to the Force and her calling to be a Jedi. I thought she might be Rens younger sister.I supposed that once Ren had turned to the darkside (the heartache of which may have contributed to the separation of Han and Leia . Leia then finding herself pregnant and alone,may have decided to hide her daughter, (to protect her from following the same path as her brother).Maybe Ren and Rei are too similar in age to support this theory. so alternatively could Leia have had twins and separated them as infants for the same reason she was separated from Luke.