Leviticus 18:11 · Bible study
Leviticus 18:11 Commentary: Why Repeat the Sister Prohibition?
Hebrew · 5 what the commentators say
Meaning in one sentence
Why does Leviticus 18:11 forbid relations with a half-sister when verse 9 already does? A close look at the wording, family structure, and ancient context.
Research Summary
- Meaning: prohibits sexual relations with a half-sister on the father’s side.
- Key words: “nakedness” (erwah; sexual exposure), “conceived” (mowledeth; offspring), “sister” (achot; any half-sister).
- Main debate: whether this verse repeats v.9 for clarity or adds a distinct prohibition.
- Theological theme: God sets boundaries within the family to protect identity, lineage, and holiness.
- Best use: preaching on the goodness of God’s design for family, and as a foundation for understanding biblical sexual ethics.
Translation Comparison
BSB Berean Standard Bible 2020
You must not have sexual relations with the daughter of your father’s wife, born to your father; she is your sister.
WEB World English Bible 2000
“‘You shall not uncover the nakedness of your father’s wife’s daughter, conceived by your father, since she is your sister.
KJV King James Version 1769
The nakedness of thy father’s wife’s daughter, begotten of thy father, she is thy sister, thou shalt not uncover her nakedness.
ASV American Standard Version 1901
The nakedness of thy father’s wife’s daughter, begotten of thy father, she is thy sister, thou shalt not uncover her nakedness.
YLT Young's Literal Translation 1898
`The nakedness of a daughter of thy father's wife, begotten of thy father, she is thy sister; thou dost not uncover her nakedness.
Darby Darby Bible 1890
The nakedness of thy father's wife's daughter, begotten of thy father: she is thy sister: thou shalt not uncover her nakedness.
Douay-Rheims Douay-Rheims Bible 1899
Thou shalt not uncover the nakedness of thy father's wife's daughter, whom she bore to thy father: and who is thy sister.
Translations in other languages (10 available)
La desnudez de la hija de la mujer de tu padre, engendrada de tu padre, tu hermana es, su desnudez no descubrirás.
A nudez da filha da mulher de teu pai, gerada de teu pai, tua irmã é, sua nudez não descobrirás.
Tu ne découvriras point la nudité de la fille de la femme de ton père, née de ton père. C’ est ta sœur.
Du sollst die Blöße der Tochter deines Vaters Weibes, die deinem Vater geboren ist und deine Schwester ist, nicht aufdecken.
De schaamte van de dochter der huisvrouw uws vaders, die uw vader geboren is (zij is uw zuster), haar schaamte zult gij niet ontdekken.
Non scoprirai la nudità della figliuola della moglie di tuo padre, generata da tuo padre: è tua sorella.
Sromoty córki żony ojca twego, która się narodziła z ojca twego, siostra twoja jest, nie odkryjesz sromoty jej.
Наготы дочери жены отца твоего, родившейся от отца твоего, она сестра твоя [по отцу], не открывай наготы ее.
你繼母 從你父親 生 的女兒 本是 你的妹妹，不可 露 她的下體。
Or your father's wife's daughter, the child of your father, for she is your sister.
Verse in Context
Original Language (Biblical Hebrew)
Old Testament · Biblical Hebrew · Leviticus 18:11
Source: STEPBible TAGNT/TEHB (CC-BY 4.0). Click or tap a morphology code to see the full parsing.
Scholars' Consensus
Commentators agree that this verse forbids sexual relations with a half-sister on the father’s side. The wording makes this explicit: she is the daughter of your father’s wife and conceived by your father, so she is your sister. Keil and Delitzsch distinguish this case from verse 9. Verse 9 addresses the son from a second marriage who might marry a half-sister from the first marriage. Verse 11 addresses the son from a first marriage whose stepmother bears a daughter to the father. Both are prohibited. Gill notes that some Jewish interpreters see verse 11 as a confirmation of verse 9, or as referring to a stepdaughter without blood tie, but the phrase “begotten of thy father” points to a biological half-sister. Matthew Henry treats it as part of the comprehensive list of incest prohibitions, reinforcing the general rule that no one may approach near kin. The repetition underscores the importance of boundaries in the family.
How settled is the interpretation?
Interpretive difficulty: Medium
Main views:
- Redundant confirmation: v.9 already covers half-sisters; v.11 applies the same rule to the son from a first marriage (Keil).
- Distinct stepfamily case: Some read it as a stepdaughter not blood-related, but the phrase 'begotten of thy father' limits it to biological (Gill).
What is clear: Sexual relations with a half-sister on the father’s side are forbidden.
What Scholars Agree and Debate
| Topic | Agreed | Debated |
|---|---|---|
| Relation to Leviticus 18:9 | Both verses forbid sexual relations with a half-sister. | Some (Keil) distinguish the son addressed; others see it as a clarifying repetition. |
| Scope of 'sister' | Includes half-sisters by the same father. | Whether it also includes full sisters (already in v.9) or only half-sisters by a later wife. |
| Step-family interpretation | The phrase 'conceived by your father' points to biological relation. | Some Jewish interpreters (Karaites) applied it to a non-biological stepdaughter raised in the household. |
| Purpose of the prohibition | God commands these limits for holiness and the protection of the family. | Whether the primary concern is social order, ritual purity, or both. |
Historical & Cultural Context
Leviticus 18 opens a section of the Holiness Code dedicated to sexual ethics. The preamble (v.1, 5) calls Israel to be holy because God is holy and warns against imitating the practices of Egypt and Canaan. The specific prohibitions of verses 6, 18 cover relationships by blood and marriage, reflecting the extended family structures common in the ancient Near East. In a polygynous household, a man might have children by multiple wives. A “father’s wife” could be a stepmother. Her daughter might be a child from a previous marriage or a child she bore to the father.
Verse 11 uses the Hebrew term mowledeth, meaning “offspring” or “one born,” to specify that the girl is the father’s biological daughter. This closed any loophole: even if she was raised as a stepchild, blood relation made her a sister. The phrase “uncover nakedness” is a euphemism for sexual intercourse. It appears twenty-one times in this legislation and consistently denotes illicit sexual contact.
The repetition of the sister prohibition in verses 9 and 11 may have been necessary to prevent confusion in blended families where a woman married into a household with children from a previous marriage. By stating “she is your sister,” the law affirms that family bonds are defined by parentage, not household arrangements alone. These boundaries protected inheritance lines, prevented rivalry, and upheld the dignity of women as persons, not objects to be passed between men.
Textual Notes
The consulted sources note no significant textual variants for this verse. The Hebrew text is consistent across manuscripts and versions. The Greek Septuagint treats the two clauses separately, but this does not affect the meaning.
Reception History
This verse has been read within the broader tradition of the incest prohibitions of Leviticus 18. Early Jewish interpretation (e.g., the Mishnah and Talmud) used verses like these to build a fence around forbidden relationships, extending the list to include step-relations even where no blood tie existed. Christian commentators from the Reformation onward saw the verse as reinforcing the natural law against incest. Matthew Henry (1710) groups it with the other prohibitions as “wholesome restraints.” The verse has also been invoked in discussions of marriage between adopted or step-siblings, though the text itself is limited to blood relations. Across traditions, the principle that close family members are not fit marriage partners has been widely affirmed.
Preaching This Verse
Three-point outline
- God’s commands protect the family structure. The prohibition guards the integrity of the family unit, preventing confusion and harm.
- The prohibition covers all sisters, including half-sisters. Blood relation through the father makes her a sister, even if the mother is different.
- The repetition shows God’s care for clarity in complex situations. Blended families needed explicit guidance, and God provided it.
Five-point outline
- Application to half-siblings. The law applies to half-sisters by the same father, not just full sisters.
- Distinction from step-relations. The phrase “conceived by your father” limits the prohibition to blood ties.
- Family defined by parentage. Marriage does not create a sister; birth does.
- Preventing confusion in blended families. The law speaks to a real social scenario.
- God’s design for human sexuality. Boundaries are not restrictions but protections for flourishing.
Illustration hooks
- A family tree drawn on paper. Half-siblings appear in one branch; the law makes clear that line cannot be crossed.
- A modern blended family at a wedding. A young person wonders if a relationship with a step-cousin is permissible. The principle of blood closeness guides the answer.
- A church policy on marriage between adopted siblings. While not directly about blood, the spirit of the law honors family bonds.
Questions your congregation is asking
- Does this mean adopted siblings cannot marry? (The text deals with blood; the principle of protecting family bonds is broader.)
- Why does God care so much about who I marry? (Because marriage shapes identity, inheritance, and holiness.)
- Is it wrong to have feelings for a step-cousin? (The law points to boundaries that keep families safe.)
Leading a Discussion
This verse helps us see that God’s instructions about family relationships are not arbitrary but designed for our good. They honor the bonds that hold a family together. As you discuss, consider how these ancient laws inform our understanding of family today.
Discussion questions
- What does this verse say about who is considered a sister? (Read the verse carefully.)
- How does this verse relate to verse 9? What is gained by repeating the prohibition?
- Why do you think God gave such specific family boundaries to Israel?
- How does this law protect vulnerable family members, especially women?
- In what ways do our modern families need similar clarity about relationships?
- How does this passage shape your view of marriage as a covenant between two individuals, not within a family?
- What does this teach us about God’s character as a God of order and care?
Word Study
The key original-language words in this verse. Select any word for its full lexicon entry — meaning, every occurrence in Scripture, and related words.
Interlinear and lexical data from STEPBible (CC BY 4.0). Commentaries are public domain.
For personal reflection
Read the devotional page — prayer, application, and "for families"
What the Commentators Say
5 public-domain commentaries, condensed into plain language.
Geneva Bible Notes Reformed 1599
The Geneva note clarifies that a half-sister, begotten by the same father, is still fully a sister under this law. Her being born from a different mother does not remove the prohibition. The relationship remains close enough that uncovering her shame is forbidden.
Gill's Exposition of the Bible Baptist 1748
Gill surveys several Jewish interpretations of this prohibition, noting that some see it as a confirmation of the earlier law against marrying a half-sister, while others understand it as a distinct restriction on marrying a stepdaughter or an adopted daughter of the father. He points out the disagreement among scholars, including Aben Ezra.
Keil & Delitzsch OT Commentary Protestant 1876
Keil-Delitzsch clarifies that the phrase "daughter of your father's wife" refers to a half-sister from a second marriage, not a full sister. They argue that the wording deliberately excludes the man's own mother and full sisters, distinguishing this prohibition from the one in Leviticus 18:9.
Lange's Commentary Reformed 1857
Lange argues these marriage laws prevent a self-centered retreat into one's own bloodline. By forcing families to form bonds with outsiders, the law counters what he calls "family egoism" and builds a wider web of love, expanding the community through ever-new relationships.
Matthew Henry's Commentary Reformed/Presbyterian 1710
Henry emphasizes that these prohibitions rest on God's own authority and the natural bonds of family. He stresses that approaching near kin violates the honor due to parents and corrupts the sacred order of relationships, making such acts not merely unclean but wicked.