Leviticus 20:21

17 If a man marries his sister, whether the daughter of his father or of his mother, and they have sexual relations, it is a disgrace. They must be cut off in the sight of their people. He has uncovered the nakedness of his sister; he shall bear his iniquity.

18 If a man lies with a menstruating woman and has sexual relations with her, he has exposed the source of her flow, and she has uncovered the source of her blood. Both of them must be cut off from among their people.

19 You must not have sexual relations with the sister of your mother or your father, for it is exposing one’s own kin; both shall bear their iniquity.

20 If a man lies with his uncle’s wife, he has uncovered the nakedness of his uncle. They will bear their sin; they shall die childless.

21 If a man marries his brother’s wife, it is an act of impurity. He has uncovered the nakedness of his brother; they shall be childless.

22 You are therefore to keep all My statutes and ordinances, so that the land where I am bringing you to live will not vomit you out.

23 You must not follow the statutes of the nations I am driving out before you. Because they did all these things, I abhorred them.

24 But I have told you that you will inherit their land, since I will give it to you as an inheritance—a land flowing with milk and honey. I am the LORD your God, who has set you apart from the peoples.

25 You are therefore to distinguish between clean and unclean animals and birds. Do not become contaminated by any animal or bird, or by anything that crawls on the ground; I have set these apart as unclean for you.

Read all of Leviticus 20