Leviticus 18:9

18:9 You must not have sexual intercourse with your sister, whether she is your father’s daughter or your mother’s daughter, ¹  whether she is born in the same household or born outside it; ²  you must not have sexual intercourse with either of them. ³ 

Leviticus 18:11

18:11 You must not have sexual intercourse with the daughter of your father’s wife born of your father; she is your sister. You must not have intercourse with her. ⁴ 

[18:9]  ¹ tn Heb “the daughter of your father or the daughter of your mother.”

[18:9]  ² tn Heb “born of house or born of outside.” CEV interprets as “whether you grew up together or not” (cf. also TEV, NLT).

[18:9]  ³ tc Several medieval Hebrew mss, Smr, LXX, and Syriac have “her nakedness” rather than “their nakedness,” thus agreeing with singular “sister” at the beginning of the verse.

[18:11]  ⁴ tn Heb “The nakedness of the daughter of your father’s wife born of your father, she is your sister; you must not uncover her nakedness.” That is, a half sister, the daughter of the man’s father by another wife, who is not the man’s mother, is to be considered a true sister. Therefore, the man must not have sexual intercourse with her.