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Is Incest Illegal in California?

Posted by Sam Israels | Oct 27, 2025

California law forbids sexual relations, including sexual intercourse, between individuals who are within degrees of consanguinity that render marriage incestuous.

Is Incest Illegal in California?
PC 285 prohibits sexual intercourse or marriage between individuals who are closely related by blood.

This includes parents and children, ancestors and descendants, siblings, and uncles or aunts with their nieces or nephews.

Incest is considered a felony. It encompasses acts such as sexual intercourse, fornication, and adultery. This law applies to individuals aged 14 and older.

Penalties for incest can include imprisonment, and offenders may also be required to register as sex offenders as outlined in Penal Code 290 PC, under the three-tier registration system established by Senate Bill 384.

Inbreeding between closely related individuals can lead to birth defects, which is why many states regulate incest. Each state defines incest differently. In California, incest is defined under Penal Code 285 PC.

A conviction for incest can result in up to 3 years in prison, fines of up to $10,000, and a requirement to register as a sex offender for 20 years.

Key Takeaways

  • Under this law, "sexual intercourse" means any penetration of the penis of one person with the other's genitalia, regardless of how slight.
  • In the state, sexual acts between family members are not legally classified as incest. This is because California law mainly focuses on genetic inbreeding, which leads to a higher risk of birth defects. Only sexual acts that could lead to pregnancy are regarded as incest.
  • Incest is classified as occurring only between relatives aged 14 or older. If one or both individuals are under 14, the act likely qualifies as a different sex crime, such as Penal Code 261.5 PC for statutory rape or Penal Code 288 PC for lewd acts on a minor under 14.
  • Incest remains a criminal offense regardless of consent between both parties.
  • Marriage in an incestuous relationship is still considered incest, even without sexual activity.
  •  According to state law, a marriage ceremony between such individuals is regarded as the same as engaging in sexual intercourse.
  • A related offense is outlined in Penal Code 281 PC, which criminalizes marrying another person while still being married to someone else. The penalties for committing bigamy are specified in Penal Code 283 PC.

What is the Content of PC 285?

Penal Code 285 PC says, "Persons being within the degrees of consanguinity within which marriages are declared by law to be incestuous and void, who intermarry with each other, or who, being 14 years of age or older, commit fornication or adultery with each other, are punishable by imprisonment in the state prison."

In simple terms, this law makes marriage or sexual relations between close relatives a felony. Notably, lack of consent is not a required element for guilt under this statute. This means that even if both parties agree, they can still be convicted.

The relatives who are prohibited from marrying or having sex include parents and children, siblings, half-siblings, grandparents and grandchildren, as well as uncles, aunts, nieces, and nephews. 

What Is Considered Incest?

In simple terms, California considers incest to be either marrying or engaging in sexual activity with a family member. To establish this, prosecutors need to prove certain elements of incest, which include the following:

  • You have either married someone or had sexual relations with another person.
  • Both you and the other individual were at least 14 years old at that time.
  • You and the other individual are related in a manner that state law deems incestuous.

What Relationships Are Classified as Incestuous?

The State of California mainly regards sexual relations between closely related individuals as incest. Consequently, state law considers sexual activity between any of the following relatives to be incestuous.

  • Parent and child
  • Grandparent and grandchild
  • Great-grandparent and great-grandchild
  • Brother and sister
  • Half-brother and half-sister
  • Uncle and niece
  • Aunt and nephew.

What Are the Consequences of Incest?

Incest is a serious crime in California. A conviction could result in the following penalties:

  • Sixteen months, or two to three years in state prison
  • A fine of as much as $10,000
  • You must renew your registration as a Tier 2 offender on the California sex offender registry annually or whenever you move, for the next 20 years.

What are the Defenses Available Under PC 285?

Being charged with incest in California is a serious issue, but a skilled California criminal defense attorney can explore legal defenses to challenge the charges. One possibility is arguing that you were unaware of the familial relationship. Although uncommon, there are cases where two individuals engage in an incestuous relationship without realizing they are related.

For example, if spouses separate, remarry, lose contact, and have other children in subsequent marriages, you could accidentally marry someone who is actually your half-brother or half-sister. If your lawyer can prove that you were unaware of the relationship, the incest charge might be dismissed.

It could be argued that you were under 18 when the relationship began, with the other person being an adult. Although this still qualifies as incest, California law assigns less liability to minors in such cases and more to adults. If you were under 18 at the start of the incest, the prosecutor may consider dropping the charges.

You might argue that you were falsely accused. It's common for estranged spouses, family members, or others to level false allegations of incest against an ex-partner, often driven by spite or revenge.

Luckily, these accusations are usually defensible because they lack supporting evidence and are based solely on a he-said-she-said situation. A skilled attorney can typically create reasonable doubt in such cases. For more information, contact our criminal defense law firm, Cron, Israels & Stark in Los Angeles, CA.

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About the Author

Sam Israels
Sam Israels

Sam J. Israels is a Law Firm partner with the Law Offices of Cron, Israels, & Stark. Mr. Israels received his J.D. degree from the Santa Clara University School of Law. Mr. Israels also previously worked at the Los Angeles Office of the City Attorney. He is admitted to practice law in the State o...

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