Genesis 46:26-27
6 All those who went to Egypt with Jacob—those who were his direct descendants, not counting his sons’ wives—numbered sixty-six persons. 27 With the two sons who had been born to Joseph in Egypt, the members of Jacob’s family, which went to Egypt, were seventy in all.
This verse says that 66 descendants went down to Egypt with Jacob. If you include Joseph's sons, the count goes up to 70. How can this be so? Shouldn't it only go up to 68 if Joseph's two sons are the only thing increasing the count?