Leviticus 18:17 Commentary: The Prohibition of Mother-Daughter Relationships

Leviticus 18 opens with a warning not to follow the practices of Egypt or Canaan (vv. 3, 4). The laws that follow, including the prohibition in verse 17, set Israel apart from surrounding nations where incestuous marriages were sometimes tolerated or even expected. For example, in some ancient Near Eastern cultures, a man might marry sisters or a mother and daughter to consolidate property or alliances. Israel's law draws sharp boundaries: sexual intimacy belongs within defined kinship circles, not across generations or between close relatives.

The euphemism “uncover nakedness” appears repeatedly in this chapter. It refers to sexual intercourse, whether inside marriage or outside it, as Poole explains for the similar phrase “approach to” (v. 6). The term laqach (“take”) can mean “marry” (as in taking a wife), but the broader context of uncovering nakedness suggests the prohibition includes any sexual relationship, not only formal marriage. Gill cites Jewish sources who debated this point, showing that the precise scope was already discussed in rabbinic tradition.

The word zimah (translated “wickedness” in most versions) carries weight. It originally means a plan or device, but in the OT it consistently denotes malicious, calculated evil, especially sexual violation. Amos 2:7 uses it for a man and his father sharing a woman, an act that profanes God's holy name. The land itself, the text later warns, will vomit out inhabitants who commit such offenses (v. 28). The prohibition is not arbitrary; it preserves the integrity of family relationships and protects the vulnerable from exploitation.

The supplied sources note no significant textual variants for Leviticus 18:17. The Masoretic Text is consistent across manuscripts, and the ancient versions (LXX, Vulgate) reflect the same reading. The only minor variation concerns the word zimah (wickedness), which appears in some Hebrew manuscripts with slightly different pointing, but the meaning is unaffected.

Across Jewish and Christian traditions, this verse has been consistently interpreted as a firm prohibition against sexual relations with a woman and her daughter or granddaughter. Early Jewish interpreters like the Targum of Jonathan rendered zimah as “whoredom,” emphasizing the gravity. Medieval rabbis debated the exact conditions (marriage vs. casual sex), as Gill reports. In Christian history, the verse was used in canon law and moral theology to define incest within extended family networks. Reformers like Matthew Henry and the Geneva Bible editors read it as part of God's protective order for families. The verse has rarely been the focus of major theological controversy; instead, it stands as one of several clear boundaries that distinguish God's people from the surrounding nations.

Three-point outline

1. Boundaries protect family. The law forbids a man from having sexual relations with both a woman and her daughter or granddaughter. This preserves clear generational lines and prevents the kind of confusion that destroys trust in households.
2. Intent matters. The prohibition covers both marriage and casual sex. It is not about legal loopholes, whether the mother is married or just deflowered. The relationship itself, once established, creates a permanent connection that forbids intimacy with her close female relatives.
3. Holiness is the goal. The same chapter begins with “I am the LORD your God.” These laws are not merely social rules; they are part of Israel's identity as a holy people. When families honor these boundaries, they reflect God's order and protect the vulnerable.

Five-point outline

1. The command: no sexual relations with a woman and her daughter (v. 17a).
2. The extension: no relations with her granddaughters through son or daughter (v. 17b).
3. The reasoning: “they are near kinswomen”, the woman and her offspring share one flesh.
4. The verdict: “it is wickedness” (zimah), a term for calculated, depraved sin.
5. The penalty (Lev 20:14): if a man marries a woman and her mother, both he and they are burned.

Illustration hooks

• A man begins a relationship with a single mother. After they break up, he pursues her adult daughter. The law says this is not allowed, the bond with the mother, even if brief, creates a permanent bar.
• In blended families, step-relationships can become confusing. This verse sets a clear rule: sexual intimacy with a woman forbids intimacy with any of her descendants.
• The text uses the same language of “uncovering nakedness” for all these relationships, no distinction between marriage and casual sex. This challenges the idea that only formal marriage creates such bonds.

Questions your congregation is asking

• Does this apply if the man only dated the mother but never married her?
• What about step-daughters or adopted daughters, are they covered by “her daughter”?
• Why is this sin called “wickedness” while other prohibited relationships are not labeled the same way?

This verse is part of a larger set of laws that define boundaries for sexual relationships. The passage assumes that family relationships create permanent ties that cannot be undone by divorce or distance. As you discuss this text, pay attention to how the law protects family structure, especially the vulnerable women and children who could be exploited in such entanglements.

Discussion questions

1. Read Leviticus 18:17 and 20:14 together. What additional information does the second passage provide about this prohibition?
2. The Hebrew word laqach (“take”) can mean “marry.” But the command pairs it with “to uncover nakedness.” Does the verse require marriage, or does it forbid any sexual relationship? What difference does it make?
3. Why do you think the law specifically forbids a man from having sex with both a woman and her daughter, rather than just forbidding incest in general?
4. The chapter connects these laws to the practices of Egypt and Canaan. What does that context tell us about why these boundaries matter for God's people?
5. How does a verse like this shape the way Christians think about family relationships today, especially in blended families or situations where there is no marriage contract?
6. Leviticus 18:17 is rarely preached. Why might that be? What makes this text difficult or uncomfortable to address?
7. This law protects the daughter and granddaughter from being exploited through a prior relationship with the mother. How does this passage affirm the dignity of every person, even those not mentioned in the text?