Exodus 6:20

And Amram took him Jochebed, his father's sister, to wife; and she bare him Aaron and Moses; and the years of the life of Amram were an hundred and thirty and seven years. Cf 1 Chronicles 6:1. Note that the sum of the ages of these three generations, plus the age of Moses at the time of the Exodus, is four hundred eighty-seven years; so there is no difficulty in making Bible chronology fit. of the three children of Amram and Jochebed, Aaron was three years older than Moses, and Miriam was older than either.