Incest Laws and Criminal Charges

The basics of state incest laws and penalties.

By , Attorney · UC Berkeley School of Law
Updated by Rebecca Pirius, Attorney · Mitchell Hamline School of Law
Updated January 08, 2024

The crime of incest is committed when people who are related to one another engage in sexual activity, get married, or live together. While the precise behavior that is considered incest varies across different states and cultures, almost all societies consider some forms of incest taboo, and laws reflect those beliefs.

How Is Incest Defined?

Incest is defined differently by state. In the United States, incestuous child sexual abuse is always a crime, and incest between adults is a crime in all but a few states.

Incest Defined as Sexual Relations, Marriage, or Both

In some states, incest is limited to sexual activity. In other states, people can commit the crime of incest by engaging in sexual activity, marrying, or living together romantically.

Incest Defined as Blood Relations, Marital Relations, or Both

Some states limit incest laws to individuals related by blood (consanguinity), while others extend these laws to those related by marriage (affinity). Generally, state incest laws ban intimate relations between children and parents, brothers and sisters, and grandchildren and grandparents. Some states also ban relations between aunts, uncles, nieces, nephews, and cousins.

Laws vary as to half- and step-relatives and adopted relatives. Second and third cousins are generally free to marry and first cousins are free to be together in most states. In a few states, incest laws are limited to heterosexual sexual relationships, where a relationship could result in the conception of a child.

Why Is Incest a Crime?

Incest laws date back decades. Many were originally enacted to promote certain family values, prevent what was considered immoral conduct, and avoid genetic disorders in offspring. As family values and concepts of morality have changed, some state's laws have kept up while others have not.

Several states changed their incest laws to prohibit sexual abuse of children by close relatives and limit prohibitions on consensual adult relations. Some states amended the wording of their incest laws to reflect right-to-marry laws. Others have left old language in law, letting prosecutors be the judge of whether to enforce such laws or not.

Is Incest Legal in Any State?

All states prohibit incest when one party is a child. Nearly all states also criminalize incest between adult relatives. Some legal scholars have argued that incest laws as applied to adults should be rethought. Rhode Island repealed its criminal (adult) incest statute in 1989, and New Jersey law imposes no criminal penalties for incest where both parties are adults, although marriages between related adults in both states are still void. Other states also prohibit marriage between related people, in addition to imposing criminal penalties for incest.

Incest Crimes Involving a Child Victim

While adult incest is not very common, many, many children are the victims of incest. In all states, sexual contact with a child under the age of consent (usually between 16 and 18) is a form of child sexual abuse. Up until the age of consent, any sexual behavior against a child—including incestuous sexual activity—is considered a sex crime.

Some states punish incest more severely than other sex crimes against children. So, while it is illegal for anyone to engage in consensual sexual activity with a young child, people who sexually abuse a child, grandchild, niece, or nephew can face longer prison terms. Of course, people who commit sexual acts by force or without the other person's consent can also be charged and convicted of sexual battery, assault, or both.

In some states, consensual sexual relations between older teens and related adults are a form of statutory rape. In such a state, an intimate relationship between a 17-year-old girl and her older half-brother might be considered statutory rape, even if a sexual relationship between the girl and an unrelated man would not be criminal. In such states, the determining fact is the familial relationship between the two people. It does not matter whether the victim acquiesced to or even pursued the intimate relationship. In some states, sex with a teen is also illegal if the sex act occurs between two people in the same household, whether they are related or not.

Is Incest a Felony?

Most states impose felony penalties for incest crimes. Harsher penalties often apply when:

  • one party is a child and the other is an adult
  • a victim is a young child (such as younger than 14), or
  • the defendant has prior sex offense-related convictions.

Felony convictions generally result in prison time, fines, or both. A person might also be required to register as a sex offender. Almost all sex crimes against children require sex offender registration.

Defenses to Incest Charges

A person charged with incest may have one or more defenses available. Many incest laws require knowledge on the part of the defendant. If a person has no idea their sexual partner is a relative, this may be a defense to incest charges. Some states allow limited marriage defenses. Depending on how the law is written, another defense may be that the partners did not have sexual intercourse.

Obtaining Legal Assistance

If you are charged with incest, contact a local criminal defense attorney immediately. A conviction for a sex crime can have serious and lasting ramifications, including time in prison and lifetime sex offender registration. An attorney will be able to explain the legal process to you and help you present the strongest possible defense

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