Is It Illegal to Marry Your Cousin in California? Here’s What the Law Says

The practice of marrying one’s cousin has been a subject of debate and varying levels of acceptance throughout history and across cultures. While some societies have embraced cousin marriage, others have outlawed it due to concerns about genetic risks and social implications. In the United States, the legality of cousin marriage differs from state to state, leaving many with questions about its permissibility. California, as one of the more liberal states, stands out in its approach.

Cousin Marriage Laws in California

California is among the states in the US that permit marriage between first cousins. Unlike some states with age restrictions or requirements for genetic counseling, California has no specific conditions attached to the legality of first-cousin unions. This means that first cousins of any age who meet the standard marriage requirements in California (legal age, mental capacity, etc.) are free to wed.

The Debate Surrounding Cousin Marriage

The permissibility of cousin marriage is a multifaceted issue with both supporters and detractors. Here’s a breakdown of the primary arguments on either side of the debate:

Arguments in Favor:

  • Individual Liberty: Advocates of cousin marriage often emphasize the right of consenting adults to choose their partners regardless of familial ties. They argue that the government should not interfere in personal relationships.
  • Cultural and Religious Traditions: In some cultures and religions, cousin marriage has been a long-standing practice. Supporters may argue that laws against cousin marriage disrespect these traditions and infringe on religious freedom.

Arguments Against:

  • Genetic Risks: The primary argument against cousin marriage centers on the increased risk of birth defects and genetic disorders in offspring. Since cousins share a portion of their genes, there is a higher chance that they both carry recessive traits for harmful conditions.
  • Social and Ethical Considerations: Opponents of cousin marriage may raise concerns about the potential for social stigma, family dynamics, and the blurring of familial roles.

Genetic Risks Associated with Cousin Marriage

It’s crucial to understand the scientific basis for concerns about genetic risks in cousin marriages.

  • Recessive Disorders: Many genetic diseases are recessive, meaning that a person needs two copies of the defective gene to develop the condition. Close relatives are more likely to carry the same recessive genes, increasing the chance their offspring will inherit two copies.
  • Increased Risk: While the overall risk remains relatively low, studies suggest that children of first-cousin marriages have a slightly higher chance of birth defects and genetic disorders compared to children of unrelated parents.
  • Genetic Counseling: Couples considering cousin marriage are often advised to seek genetic counseling. This can help them understand their individual risks and make informed decisions about family planning.

Cultural and Religious Perspectives

The view on cousin marriage varies across cultures and religions. It’s important to understand these perspectives to gain a well-rounded picture of the issue.

  • Historical and Religious Acceptance: In some cultures, cousin marriage has been historically common and even preferred. It has been seen as a way to strengthen family ties and keep property or resources within a family. Certain religions, including some branches of Islam, Judaism, and Christianity, have traditionally permitted or even encouraged cousin marriage.
  • Differing Views: However, not all religions embrace cousin marriage. Some denominations within Christianity and other faiths may view it negatively. Additionally, cultural perspectives have shifted over time, and in many Western societies, cousin marriage is increasingly seen as unusual or taboo.

Legal Trends and the Future of Cousin Marriage

The legal landscape surrounding cousin marriage in the United States is constantly evolving.

  • Changes in Other States: Several states have recently changed their laws regarding cousin marriage. Some have lifted previous bans, while others have added restrictions or counseling requirements. These shifts indicate ongoing public discourse and potential changes.
  • Potential for Change in California: While California currently has a permissive stance on cousin marriage, it’s possible that the law could change in the future. Heightened awareness of genetic risks or changing social norms may influence future legislation.


California’s law allowing first-cousin marriage reflects the state’s stance on individual freedom and limited government intervention in personal choices. The debate around cousin marriage highlights the complex interplay of personal liberty, scientific concerns, and cultural norms.

While California law is clear, individuals considering cousin marriage must weigh the potential benefits, the increased genetic risks, and the varying social and cultural views on such a union. Genetic counseling can provide valuable guidance for couples seeking to make informed decisions about their future.


Here’s a list of reputable sources for further research into cousin marriage:

  • National Society of Genetic Counselors ( – provides information about genetic risks and the role of genetic counseling.
  • ( – offers research and data on consanguinity, including cousin marriage.
  • The Pew Research Center ( – conducts research and provides data on public opinion and trends related to cousin marriage.
  • State government websites of California and other states for specific legal statutes regarding cousin marriage.

Important Note: This article aims to provide information regarding cousin marriage laws and the debate surrounding this topic. It’s essential to consult with qualified professionals, such as lawyers and genetic counselors, for personalized advice about any legal or health-related concerns.

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MBS Staff
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