When you think about the legalities of marriage in the United States, your mind probably jumps to age requirements or maybe residency rules. But there’s a topic that usually stays in the shadows of family reunions and hushed whispers: first cousin marriage. Honestly, it's one of those things most people assume is universally banned across the board.
You’d be wrong.
In reality, the map of the U.S. is a patchwork of surprisingly permissive laws and strict prohibitions. It’s not just a relic of the past, either. Laws are shifting right now. As of early 2026, the legal landscape has seen some major changes, with states like Connecticut and Tennessee recently tightening their rules to join the majority of the country in banning the practice.
What States Allow First Cousins to Marry Today?
If you’re looking for a straight "yes" or "no" answer, you won't find one that covers the whole country. Marriage is a state-level issue. This means a couple could be legally wed in one state and technically committing a crime if they move across a certain border.
Currently, about 18 states (plus the District of Columbia) allow first cousins to marry without any specific hurdles or biological "tests."
The "No Questions Asked" States
These are the places where the law doesn't treat first cousins any differently than two strangers meeting at a bar. If you’re over 18 and not already married, you’re good to go.
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- Alabama
- Alaska
- California
- Colorado
- Florida
- Georgia
- Hawaii
- Maryland
- Massachusetts
- New Jersey
- New Mexico
- New York
- North Carolina (with a small catch: "double first cousins" are prohibited)
- Rhode Island
- South Carolina
- Tennessee (Note: A 2024 ban was enacted, but it did not void existing marriages)
- Vermont
- Virginia
It’s kind of wild when you think about it. You can drive from a state where it’s a felony to a state where it’s totally fine in just a couple of hours.
The Middle Ground: Exceptions and Restrictions
Then you have the "it’s complicated" states. These are jurisdictions that say, "Okay, you can marry, but only if you meet certain criteria." Usually, these criteria are designed to prevent the couple from having children, based on the historical (and often debated) concern over genetic defects.
Take Arizona and Wisconsin, for example. In these states, first cousins can only marry if both parties are 65 or older. Why? Basically, the law assumes you aren't going to have biological children at that age. If you’re younger, one of you has to prove infertility to get that marriage license.
Utah has a similar vibe but sets the age slightly lower at 65, or 55 if a court finds that they are unable to reproduce. Illinois is even more specific—you have to be at least 50 years old.
Maine takes a different route. Instead of age, they focus on science. Cousins can marry there, but they have to provide a certificate from a physician stating they’ve received genetic counseling. It’s a way of saying the state won't stop you, but they want you to know the risks.
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Recent Legal Shifts: Why the Map is Changing
If you had asked about this a few years ago, the list of "legal" states would have been longer.
Take Connecticut. For a long time, it was the outlier in New England. While New Hampshire had a ban, Connecticut remained open. That changed on October 1, 2025. Following a trend sparked by Tennessee’s 2024 ban, Connecticut lawmakers passed a bill (HB 06918) that officially outlawed first-cousin marriage.
Representative Steve Stafstrom, who co-chaired the Judiciary Committee, pointed to modern science regarding birth defects as a primary driver. It’s a classic example of "modernizing" the family code. But here's the catch: these laws aren't retroactive. If you were married in Connecticut on September 30, 2025, your marriage is still valid. The state isn't in the business of breaking up existing families; they just don't want new ones starting that way.
The Immigration Headache
This isn't just about wedding ceremonies and family drama. For many, the question of what states allow first cousins to marry is a high-stakes immigration issue.
If a U.S. citizen marries their first cousin abroad—say, in a country where it's culturally common and perfectly legal—U.S. Citizenship and Immigration Services (USCIS) looks at the laws of the state where the couple intends to live.
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If they move to Texas or Oklahoma, where these marriages are not only void but considered criminal, they might face a "public policy" rejection. Their marriage won't be recognized for a green card. But if that same couple moves to New York or California, the federal government usually respects the marriage because the state does.
Breaking Down the "Why"
Why do some states care so much? It usually boils down to two things:
- Genetic Concerns: The most cited reason. Studies, like those referenced during the Connecticut legislative sessions, show a slightly higher risk of recessive genetic disorders. However, some researchers, like those published in the Journal of Genetic Counseling, argue the risk (about 4–6% compared to the baseline 2–3%) is often exaggerated in the public imagination.
- Social Norms: Laws often reflect the "ick factor" of the majority. In many cultures globally, cousin marriage is a way to keep resources and trust within a family. In the U.S., the cultural shift toward "nuclear" families made cousin marriage feel like a taboo.
What You Need to Know If You’re Considering This
If you or someone you know is navigating this, don't just wing it. The legalities are dense.
- Check the "Void" Statutes: Some states won't let you marry there, but they will recognize a marriage performed elsewhere. Other states, like Delaware, have historically fought against recognizing out-of-state cousin marriages entirely.
- Criminal Liability: In a few states, like Texas, "incest" laws are written broadly enough that first-cousin marriage could technically lead to criminal charges. It’s rare for people to be prosecuted for a consensual marriage, but the law is on the books.
- Genetic Counseling: Even if it’s not required (like in Maine), it’s a smart move. Modern medicine can give you a much clearer picture of actual risks than a law written in 1920.
The reality of what states allow first cousins to marry is that the U.S. is moving toward more restrictions, not fewer. If you’re in a state where it’s legal today, there’s no guarantee it will stay that way five years from now.
Before making any life-altering decisions, your best bet is to consult with a family law attorney in the specific state where you plan to reside. They can look at the latest statutes—like the 2025 Connecticut shift—to ensure your union is protected under the law. Check the specific "Consanguinity" statutes in your state’s marriage code to see exactly how your relationship is defined.