Around two dozen countries do not criminalize consensual sex between adult relatives. The list includes France, Spain, Portugal, Belgium, Luxembourg, the Netherlands, Russia, Latvia, Brazil, Argentina, Japan, South Korea, Turkey, Thailand, and Ivory Coast, along with a handful of U.S. states and several countries where legality depends on specific conditions. In every one of these places, the picture is narrower than it first appears: marriage between close relatives is almost always void, sex with a minor remains a serious offense, and any coercion or abuse of family authority triggers heavy penalties.
Western Europe
France is the clearest example. Its penal code contains no provision criminalizing consensual sex between adult relatives, and the silence is deliberate rather than an oversight. Prosecution follows only when a minor is involved, when one party holds authority over the other, or when force or coercion is present.
Spain reached the same place by a different route. Incest was a crime under Francoist-era law until 1978, when democratic reform rewrote the penal code around sexual freedom and autonomy instead of a fixed moral framework. Two consenting adult siblings face no criminal liability for a private relationship under current Spanish law.
Portugal, Belgium, and Luxembourg also have no criminal provision against consensual adult incest. The Netherlands does not criminalize it either, though marriage between close relatives remains prohibited. Russia and Latvia round out the European countries with no criminal penalty for adult relatives who engage in consensual sexual conduct.
Countries Where Legality Depends on the Circumstances
Several European systems sit between full legality and a flat ban.
Italy treats incest as criminal only when the relationship provokes what the law calls “public scandal.” A private relationship between two adult relatives that never becomes public knowledge falls outside the statute. Once it becomes widely known and generates community outrage, prosecution becomes possible.
Sweden decriminalized sex between half-siblings in 1973 but kept the prohibition for full siblings and for parent-child relationships. Marriage between half-siblings requires a government dispensation.
Germany goes the other direction. Section 173 of the German Criminal Code punishes sexual intercourse between consenting adult siblings with up to two years in prison. In 2008, the German Federal Constitutional Court upheld that provision in a case involving a brother and sister who had grown up separately and began a relationship as adults, citing the protection of family structures and self-determination alongside what it called a “common conviction that incest should be subject to criminal liability.”1Bundesverfassungsgericht. Criminal Liability of Sibling Incest Is Constitutional Patrick Stübing, the man in that case, took the challenge to the European Court of Human Rights, which sided with Germany on the ground that countries have wide discretion given the lack of European consensus.2vLex United Kingdom. Stubing v Germany The German statute applies only to opposite-sex intercourse between relatives; same-sex conduct is outside its scope.
Ireland has a similar quirk. Its criminal prohibition on incest reaches only opposite-sex intercourse, leaving same-sex conduct between adult relatives unaddressed by the statute.
The Americas
Brazil does not criminalize consensual sex between relatives when both parties are above the age of consent, which is 14. Argentina’s criminal code has no standalone incest provision either. Argentine sexual offense statutes focus on coercion, abuse of authority, and the involvement of minors, and when a sexual offense does occur, a family relationship functions as an aggravating factor that increases the sentence rather than an independent crime.3Anti-Slavery Law. Criminal Code of the Argentine Nation A consensual relationship between adult relatives, without coercion and without a minor, does not trigger prosecution.
The United States criminalizes incest in the great majority of states, but two are exceptions. New Jersey has no statute reaching consensual sexual activity between adult relatives; its sexual assault laws cover conduct involving minors and non-consensual acts, but not private consensual relationships between related adults. Rhode Island does not prohibit incest between people aged 16 or older, though the state voids any marriage between close relatives.4Rhode Island General Assembly. Rhode Island Code 15-1-3 – Incestuous Marriages Void In both states, any sexual contact involving a minor or any element of coercion remains a serious felony.
Asia, the Middle East, and Africa
Japan has no criminal law against consensual incest between adults. South Korea takes a similar approach on the criminal side, though it prohibits marriage between relatives within eight degrees of kinship, one of the strictest marriage bans in the world.
Turkey’s criminal code contains no provision against consensual adult incest, reflecting the secular legal reforms Mustafa Kemal Atatürk modeled partly on European civil law. Thailand also lacks a criminal prohibition, though its age of consent is 15, so any relationship involving someone younger triggers prosecution regardless of family connection.
India does not specifically define or criminalize incest as a standalone offense, but statutes covering sexual assault, child sexual abuse, and domestic violence can reach incestuous conduct when minors or coercion are involved. Israel permits sexual relationships between adult relatives only when both parties are over 21, a higher threshold than its general age of consent. Ivory Coast, shaped by French colonial legal tradition, has no criminal incest provision.
Marriage Between Relatives Is Still Void Almost Everywhere
Legality of the sexual act is not the same thing as legal recognition of a relationship. Marriage between close relatives is banned in nearly every jurisdiction on earth, including the countries listed above. Courts treat these unions as void from the beginning, meaning the marriage was never legally valid and no divorce is needed to end it.5Cornell Law Institute. Void Marriage
The practical consequences are significant. A couple in a void marriage cannot file joint tax returns, claim spousal inheritance rights, make medical decisions for each other, or access survivor benefits. California’s Family Code is typical: marriages between parents and children, between any ancestors and descendants, between full or half siblings, and between uncles or aunts and nieces or nephews are “incestuous, and void from the beginning.”6California Legislative Information. California Code FAM – Void Marriage The countries on the list above maintain some version of this marriage prohibition even where the sexual act carries no criminal penalty.
Abuse of Authority Remains a Serious Crime
The absence of a general incest statute does not leave family sexual dynamics unregulated. Countries that decline to criminalize consensual adult incest almost always maintain robust laws against sexual abuse involving power imbalances, and those laws impose heavier sentences when a family relationship is present.
France illustrates the pattern. Rape committed by an ascendant, meaning a parent, grandparent, or adoptive parent, carries up to 20 years in prison, compared with 15 years for rape without that aggravating factor. Sexual assault by an ascendant or person with authority over the victim is punishable by up to 10 years and a €150,000 fine.7ICMEC. France National Legislation Sexual acts on a minor over 15 that involve no violence carry a two-year sentence and €30,000 fine when committed by an ascendant.
The underlying line these systems draw is around genuine consent. A parent-child relationship, even between adults, involves a power dynamic that can compromise free choice. The question a court asks is not whether the two people are related but whether the person could freely say no.
Travel Does Not Always Move You Beyond Your Home Country’s Laws
Conduct legal where it happens can still be prosecuted at home. Several countries assert jurisdiction over sexual offenses their citizens commit abroad, regardless of local law.
The United Kingdom is a pointed example. Section 72 of the Sexual Offences Act 2003 allows prosecution of any UK national or resident who commits a sexual act prohibited under UK law while abroad. The Criminal Justice and Immigration Act 2008 removed the dual criminality requirement for sexual offenses, so it does not matter whether the act was legal where it occurred. A UK citizen who engages in an incestuous relationship in France, where the conduct is lawful, could in theory face prosecution on returning to Britain.
The practical risk varies. Prosecutions for consensual adult conduct that took place abroad are extremely rare, and enforcement resources concentrate on offenses involving minors and trafficking. But the legal exposure exists. One study of 121 countries found that 55 do not require the act to be criminal in both countries before asserting jurisdiction, so the framework for prosecution is broader than most people assume.