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

When it comes to marriage laws in the United States, few topics raise more questions—and sometimes eyebrows—than cousin marriage. With regulations differing wildly from one state to another, understanding what is legal, what isn’t, and why can be a challenge. If you’re living in Missouri or planning to move to the Show-Me State, you might wonder: Is it illegal to marry your cousin in Missouri? This in-depth guide explores Missouri’s laws on cousin marriage, explains how these rules compare to other states, delves into historical context, and provides statistics, city-specific practices, and social considerations.

Understanding Cousin Relationships

Before diving into the law, it’s important to clarify terminology:

First cousin: The child of your aunt or uncle; you both share a set of grandparents.
First cousin once removed: Either the child of your first cousin or your parent’s first cousin.
Second cousin: The child of your parent’s cousin.

These distinctions matter under Missouri law, as the legality of marriage depends on the exact relationship.

Missouri’s Law on Cousin Marriage

The Statute Explained

Missouri law specifically addresses the question of cousin marriage in its statutes. The Missouri Revised Statutes § 451.020 declare that marriages between first cousins are “presumptively void.” This means such unions are not legally recognized within the state and are explicitly prohibited. The prohibition applies to both blood relatives and adopted cousins. Attempting to obtain a marriage license for a first-cousin union is unlawful, and officials who knowingly issue such a license can face misdemeanor charges.

Application in Missouri Cities

Whether you’re in Kansas City, St. Louis, Springfield, Columbia, or a smaller town like Gladstone or Sikeston, the law is the same statewide. Local marriage license offices—including those in urban centers like St. Louis City Hall or Recorder’s offices in Springfield and Columbia—explicitly deny marriage license applications for first cousins. All applicants must attest they are not related “through and including first cousins” when applying.

What About More Distant Cousins?

Missouri law makes a distinction for more distant relatives. While first cousin marriages are banned, marriages between first cousins once removed, half-cousins, and second cousins are not restricted. For example, a resident of Jefferson City could legally marry their first cousin’s child or a half-cousin, provided all other marriage requirements are met.

The Marriage License Process in Missouri Cities

Obtaining a marriage license in Missouri is designed to be straightforward, provided you meet legal requirements. Here’s how it works in major cities:

St. Louis

Both applicants must appear in person at the Recorder of Deeds office with government-issued photo IDs.
The application fee is typically around $48, payable by cash or card.
Proof that the couple are not related as first cousins is mandatory.
The license is valid for 30 days and must be used in Missouri.

Kansas City (Jackson County)

Both parties must be present for the application.
Documentation required includes valid photo identification and Social Security numbers.
The marriage license may not be issued if the applicants are first cousins.

Columbia (Boone County)

Couples may begin the process online but must finalize the license in person.
The application explicitly excludes first cousin marriages.

Other counties and cities, such as St. Charles, Platte, and Lincoln, follow the exact statutory guidelines, including barring first cousins from marrying.

A Brief History of Cousin Marriage

Cousin marriage was historically more common in the United States, including in states like Missouri. In the 19th century, up to 20% of marriages, in some small communities, could be between cousins. Over time, as migration increased and public health theories evolved, states began passing bans. Missouri’s law has remained consistent since its adoption, maintaining a strict prohibition on first cousin marriages.

National and Global Comparisons

Today, cousin marriage remains rare in the United States. Only about 0.2% of marriages in the U.S. are between individuals who are second cousins or closer, representing roughly 250,000 people nationwide. Globally, the rate is much higher—about 10% of all marriages are consanguineous (between second cousins or closer), with high prevalence in parts of the Middle East, South Asia, and North Africa.

Neighboring States: How Missouri Compares

Missouri’s stance on cousin marriage is not unique in the region.

Illinois: First cousin marriages are allowed only if both individuals are over 50 or if either is permanently sterile.
Arkansas, Nebraska, Kansas, Oklahoma, Kentucky: All ban first cousin marriages, similar to Missouri.
Tennessee: Also bans first cousin marriages outright.

For Missouri residents, this means that even if a cousin pair travels to Illinois and fits the age or fertility exception for marriage, Missouri will not recognize the union if they reside in-state.

What Is Allowed for Cousins in Missouri?

While marriage is prohibited for first cousins, Missouri law does allow other kinds of relationships:

Cohabitation: First cousins can legally live together in Missouri.
Sexual Relationships: There are no criminal penalties for consensual sexual relationships between adult first cousins.
First Cousins Once Removed and Beyond: These relationships—including marriage to a cousin’s child or second cousin—are permitted.

Real-Life Scenarios in Missouri Cities

Let’s look at how this plays out in practice:

St. Louis

A couple applying for a marriage license at St. Louis City Hall runs through a checklist with county clerks. If the applicants reveal they are first cousins, their request is denied on the spot. If they are second cousins or first cousins once removed, their application is accepted—as long as all other criteria are met.

Springfield

A similar scenario unfolds at the Recorder’s office in Springfield-Greene County. Staff routinely screen applicants for prohibited relationships; first cousin marriages are barred.

Columbia

At Boone County’s Recorder office, the explicit application guidelines state that first cousin marriages are not permitted, and applicants must attest to their relationship before a marriage license is issued.

Jefferson City

As the state capital, Jefferson City’s offices model best practices for compliance with Missouri statutes. First cousin marriage applications are rejected consistently.

Table: Missouri and Neighboring States – Cousin Marriage Laws

State	First Cousin Marriage	Exceptions	Out-of-State Recognition
Missouri	Not legal	None	Not recognized if prohibited
Illinois	Restricted	Only if both over 50 or sterile	Not recognized by Missouri
Arkansas	Not legal	None	Not recognized if prohibited
Kansas	Not legal	None	Not recognized if prohibited
Kentucky	Not legal	None	Not recognized if prohibited
Nebraska	Not legal	None	Not recognized if prohibited
Tennessee	Not legal	None	Not recognized if prohibited

Statistics: How Common Is Cousin Marriage?

Despite its legal status in some states, cousin marriage is exceedingly rare in Missouri and across the United States:

Only about 0.2% of all American marriages are between second cousins or closer.
Estimates suggest approximately 250,000 people in such marriages nationwide.
In global contrast, countries like Pakistan and parts of the Middle East see much higher rates—up to 50% in certain places.

This difference speaks to deep cultural and legal divides on family and marriage around the world.

Why Did Missouri and Other States Ban Cousin Marriage?

The rationale behind banning first cousin marriages historically included:

Concerns over genetic health risks to offspring.
Social taboos and shifting cultural norms.
The desire to broaden family connections and prevent concentrated inheritance.

Modern genetic research suggests the risks for children of first cousins are higher than unrelated couples but significantly lower than is often believed by the general public.

Are There Ever Exceptions to Missouri’s Ban?

Missouri law is one of the strictest in the nation. Unlike states like Maine (requiring genetic counseling) or Illinois (allowing first cousins to marry under age or fertility exceptions), Missouri offers no discretionary measures or medical exceptions. Age, infertility, or other circumstances do not change the legal ban.

What If You Marry Your Cousin Elsewhere?

If Missouri residents attempt to bypass the law by marrying in a state where cousin marriage is allowed, Missouri will not recognize the marriage if couples live in-state. This policy aims to prevent legal loopholes and ensure uniform enforcement throughout the state.

Legal and Personal Consequences

Marriages between first cousins are void from the beginning and hold no legal status.
Anyone issuing such a marriage license could face misdemeanor charges.
Couples may experience social repercussions due to enduring taboos, especially in smaller towns or rural areas like Warrensburg or Hannibal.

Common Questions About Cousin Marriage in Missouri

Can First Cousins Live Together?

Yes, cohabitation is not criminalized, and sexual relationships between consenting adult first cousins are not prosecuted. However, the relationship does not grant any of the legal protections or rights of marriage.

Can First Cousins Once Removed or Second Cousins Marry?

Yes, these marriages are allowed in Missouri. Relationships like these, involving individuals from different generational levels or sharing only great-grandparents, do not face legal restrictions.

Will Missouri Recognize a Valid Out-of-State Cousin Marriage?

No. Even if a couple legally marries as first cousins in another state, Missouri will not recognize that marriage for residents. This is enforced in every city and county statewide.

Practical Advice for Missouri Residents

If you are related to your partner by blood or adoption and are considering marriage in Missouri, verify your relationship degree thoroughly. Seek legal guidance if you have questions about your eligibility. County recorders and clerks in cities such as St. Louis, Kansas City, Springfield, and Columbia are well-versed in these matters and can assist with questions regarding eligibility.

Although cousin marriage has always existed throughout human history and is legal in parts of the world, it remains taboo for many Americans, especially in rural Missouri. Part of the resistance is rooted in concern over health outcomes; part is simply tradition and social norm. While public opinion is slowly shifting in some areas due to new research and changing familial structures, cousin marriages remain largely stigmatized in Missouri.

Summary

Missouri law is clear: First cousin marriages are not allowed anywhere in the state, from the streets of St. Louis to the farms of Pike County. There are no exceptions for age, fertility, or out-of-state legal marriages. The ban extends to all applications for marriage licenses and is strictly enforced in every city, whether Kansas City, Columbia, Springfield, or smaller communities.

For those considering marriage to a cousin one step further removed (once removed or more), or to a second cousin, Missouri law does not stand in your way. However, social acceptance may still vary, so understanding both legal and social landscapes is crucial.

If you have questions about your situation, contacting local marriage license offices or consulting a family law attorney is strongly recommended to ensure compliance and clarity before planning your ceremony.

Marriage laws can be both intricate and emotional. Staying informed can help avoid legal complications and help you make the right choice for your unique family circumstances in Missouri.