Deuteronomy 27:22

“Cursed [be] he that lieth with his sister, etc.] Which is forbid, (<031809>Leviticus 18:9); the daughter of his father, or the daughter of his mother; whether his sister by father or mother’s side: and all the people shall say Amen; detesting such uncleanness.”

“Compare Joshua 8:32-35. The solemnity was apparently designed only for the single occasion on which it actually took place. Deuteronomy 27:12, Deuteronomy 27:13 The tribes appointed to stand on Gerizim to bless the people all sprang from the two wives of Jacob, Leah and Rachel. All the four tribes which sprang from the handmaids Zilpah and Bilhah are located on Ebal. But in order, as it would seem, to effect an equal division, two tribes are added to the latter from the descendants of the wives, that of Reuben, probably because he forfeited his primogeniture Genesis 49:4; and of Zebulun, apparently because he was the youngest son of Leah. The transaction presents itself as a solemn renewal…”

“27:22 whether . . . the daughter of his father or his mother: Though this instruction concerns a relationship with a half sister or foster sibling, it precludes a sexual relationship with one’s full sibling as well (see Lev 18:9; 20:17).”

“Lev 18:9, Lev 20:17; Sa2 13:1, Sa2 13:8-14; Eze 22:11 Deuteronomy 27:23”