In the United States, second cousins can marry in nearly every state. No federal law prohibits it, and the consanguinity rules that states use to restrict marriage between relatives are aimed at much closer relationships. Only a small number of states extend their bans out to second cousins, so for most couples the answer to whether second cousins can marry is a straightforward yes.
Are You Actually Second Cousins
Before relying on that answer, confirm the relationship. Second cousins share a set of great-grandparents but not grandparents. Your parent and your second cousin’s parent are first cousins, which means your grandparents on that side are siblings. You are separated by four generations from your nearest common ancestor.
That distance matters legally because it is also genetic distance. Second cousins share roughly 3.13% of their DNA on average, compared with about 12.5% for first cousins and 50% for siblings. Genetic research consistently finds minimal additional health risk for children born to second-cousin couples, and that low level of shared DNA is the main reason lawmakers rarely reach this far out on the family tree.
If your relationship is actually closer than second cousin — for example, if you share a grandparent rather than a great-grandparent — a different set of rules applies, and you should check the first-cousin law in your state instead.
What State Law Says
Marriage is regulated at the state level, not the federal level. Each state sets its own rules on who can marry whom, and how far out the kinship restrictions extend. That produces a patchwork where neighboring states can treat the same family relationship differently.
For second cousins specifically, the overwhelming majority of states either explicitly permit the marriage or have no prohibition on the books, which comes out the same way in practice. A small number of states extend their consanguinity bans to include second cousins, but this is the exception. Because the list of restrictive states is short and can change, verify the law in the state where you plan to apply for your license before you commit to a date.
First-cousin marriage is a different question with a very different answer. Roughly half of states prohibit it outright, and a few others allow it only under specific conditions such as an age floor or proof that the couple cannot have children. If you have been reading about cousin marriage generally and come away with the impression that the law is restrictive, that impression comes from the first-cousin rules, not the second-cousin ones.
Moving to Another State After You Marry
One scenario catches people off guard. If you marry your second cousin in a state that allows it and then move to one of the few states that does not, does your marriage travel with you?
Federal law requires states to give full faith and credit to marriages performed elsewhere, but that protection specifically covers discrimination based on sex, race, ethnicity, or national origin.1Office of the Law Revision Counsel. United States Code Title 28 – 1738C Certain Acts, Records, and Proceedings and the Effect Thereof Consanguinity is not on that list. In practice, most states follow the common-law rule that a marriage valid where celebrated is valid everywhere, but a state with a strong public policy against the union could refuse to recognize it.
For second-cousin couples this is rarely a real problem because so few states ban the marriage in the first place. If a move to one of those states is on your horizon, though, the question is worth answering in advance. A marriage that is not recognized in your new state affects property rights, health-care decision-making authority, and tax filing status.
What Happens if a State Does Prohibit the Marriage
If you live in one of the small number of states that does extend its consanguinity ban to second cousins, the legal response to a prohibited marriage depends on how that state classifies it.
- A void marriage is treated as though it never existed. Neither spouse needs to go to court to end it, though a court order may still be useful to sort out property and other practical matters. Either party, and sometimes a third party such as a state attorney general, can raise the issue.
- A voidable marriage is legally valid until a court issues an annulment. Only the spouses themselves can challenge it, and until someone does, the marriage stands with all its usual legal effects.
Some states also have incest statutes that technically apply wherever a consanguinity ban applies. Prosecutions in cousin cases are rare, but the statutes exist. Both of these risks are almost entirely a first-cousin-and-closer issue in practice, not a second-cousin one.
Whatever the marriage’s status, children’s rights do not depend on it. Both parents retain child support and custody responsibilities regardless of whether a marriage is later voided or annulled. Courts decide custody and support on the best interests of the child. Inheritance rights for children born during a marriage that is later annulled are protected in every state.
Practical Steps Before You Apply for a License
For most second-cousin couples, the path to a marriage license looks like any other couple’s. You apply in the county where you plan to marry, and the application asks about your relationship. A few steps head off complications:
- Confirm the consanguinity rule in the state where you will apply. Most states allow second-cousin marriages; a small number do not.
- Keep a simple family tree showing the great-grandparent connection. If a shared surname prompts a question at the clerk’s office, it is faster to show than to explain.
- If a move to a restrictive state is possible, marrying first in a permissive state is prudent, though recognition after the move is not guaranteed.
- If you plan to have children, a genetic counselor can screen for specific hereditary conditions that run in your shared family line. No state requires this for second cousins, but the information can be reassuring.
Marriage license fees generally run between $20 and $115 depending on the county, and some counties offer a discount for couples who complete a premarital education course. Processing times vary, and a few states impose a short waiting period between license issuance and the ceremony.