“A man shall not take his father's wife, nor discover his father's skirt.” (Deuteronomy 22:30)
The Old Testament is a very practical system for living a prosperous and happy life. The principles it lays out are still applicable to modern life, although we are often told they have no relevance today. Sexual relationships with relatives have two potentially serious risks.
Those who work with livestock are usually aware of the consequences of inbreeding. A gene that when combined with other genes may produce a highly desirable trait, but when duplicated in both the father and mothers DNA nay result in serious genetic problems. Dwarfism is common among inbred Herford cattle, Hip problems are common among collies, and mental problems are common among Pitbulls and Poodles. Similar problems are seen in small closely knit groups which are concerned with retaining their cultural identity or purity. It is shocking to study the mental and physical decline of European royalty because they would not allow marriage to outsiders. Leviticus 18:6-13 give specific instructions to minimize this danger.
“None of you shall approach to any that is near of kin to him, to uncover their nakedness: I am the LORD.
The nakedness of thy father, or the nakedness of thy mother, shalt thou not uncover: she is thy mother; thou shalt not uncover her nakedness. The nakedness of thy father's wife shalt thou not uncover: it is thy father's nakedness.
The nakedness of thy sister, the daughter of thy father, or daughter of thy mother, whether she be born at home, or born abroad, even their nakedness thou shalt not uncover.
The nakedness of thy son's daughter, or of thy daughter's daughter, even their nakedness thou shalt not uncover: for theirs is thine own nakedness. The nakedness of thy father's wife's daughter, begotten of thy father, she is thy sister, thou shalt not uncover her nakedness.
Thou shalt not uncover the nakedness of thy father's sister: she is thy father's near kinswoman. Thou shalt not uncover the nakedness of thy mother's sister; for she is thy mother's near kinswoman.” (Leviticus 18:6-13)
Conflicts arise in any relationship, and sexual relationships are especially vulnerable to jealousy and emotional damage. Psychologists tell us that losing a mate is as traumatic as having a limb cut off, which is one reason why adultery was such a serious offense. It is compounded when it is with the mate of a close relative. These dangers are very real in the above situations, and may destroy family relationships, but the same risk involves those who are only connected by relationship to another person. Leviticus 18:14-18 deals with these situations.
“Thou shalt not uncover the nakedness of thy father's brother, thou shalt not approach to his wife: she is thine aunt.
Thou shalt not uncover the nakedness of thy daughter in law: she is thy son's wife; thou shalt not uncover her nakedness.
Thou shalt not uncover the nakedness of thy brother's wife: it is thy brother's nakedness. Thou shalt not uncover the nakedness of a woman and her daughter, neither shalt thou take her son's daughter, or her daughter's daughter, to uncover her nakedness; for they are her near kinswomen: it is wickedness.
Neither shalt thou take a wife to her sister, to vex her, to uncover her nakedness, beside the other in her life time.” (Leviticus 18:14-18)
Close association can lead to temptation unless one makes a definite decision not to get involved. Getting involved forces the family to take sides and does great emotional harm to everyone involved. Guilty parties were to be cut off from the people, either excluded or executed.