“who came out of his thigh.” The “thigh” is euphemistic for the genital organs, and the idiom “came out of his thigh” refers to his direct descendants (see commentary on Gen. 24:2). [For more information on sexual euphemisms, see commentary on Isa. 47:2].
“all the souls were 66.” So Jacob had 66 people who were his direct descendants go with him into Egypt. That number did not include his son’s wives, because they were not descendants of Jacob.