Charles Ellicott Commentary Genesis 46:26

"All the souls that came with Jacob into Egypt, that came out of his loins, besides Jacob`s sons` wives, all the souls were threescore and six;" — Genesis 46:26 (ASV)

All the souls were threescore and six. —This total is obtained by omitting Jacob, Joseph, and Joseph’s two sons. If we include these, the whole number becomes seventy, as in Genesis 46:27. In the Septuagint the names of five grandsons are added to Genesis 46:20, and thus the total is made seventy-five, as quoted by St. Stephen in Acts 7:14.