First-cousin marriage is void.
The ban targets first cousins. Confirm with your county clerk.
Allowed in Missouri and every other US state.
Neighboring states.
Cousin marriage laws change at the state line. Here's how Missouri's neighbors handle first cousins.
| State | First cousins | Details |
|---|---|---|
| Iowa | Banned | |
| Illinois | Legal with conditions | Only if both are 50 or older, or one of you can't have children. |
| Kentucky | Banned | Bans marriage "nearer of kin than second cousins," and doesn't recognize ones from other states. |
| Tennessee | Banned | Banned in 2024. |
| Arkansas | Banned | |
| Oklahoma | Banned | Also a criminal offense. |
| Kansas | Banned | |
| Nebraska | Banned |
See all 50 states on the cousin marriage map. Laws change, so confirm with your county clerk before you plan anything.
Legal is one question. Genetics is another.
Children of first cousins have roughly a 5 to 6% chance of a serious birth defect, compared with about 3% for unrelated parents. For second cousins, the extra risk is under one percentage point.
The risk comes from recessive conditions. Cousins are more likely to carry the same hidden variant from a shared grandparent. A carrier screen tells you whether you two actually do. If you don't, most of the extra risk goes away.
Not sure exactly how you're related? The cousin calculator names any relationship, and a DNA comparison settles it for good.
Cousins? Check your carriers.
The single most useful test a related couple can take before kids. One couple result, with a genetic counselor included.
Missouri cousin questions.
Can you marry your first cousin in Missouri?
No. Missouri does not allow first cousins to marry.
Can you marry your second cousin in Missouri?
Yes. Second cousins can legally marry in Missouri, as in every US state.
Can you marry your first cousin once removed in Missouri?
Usually yes. Missouri's ban targets first cousins, but check the exact statute or ask your county clerk.
Is it legal to date your cousin in Missouri?
Dating isn't regulated, but marriage and incest laws can apply to close relatives. In Missouri, first cousins can't legally marry, so a serious relationship can become legally complicated. Second cousins and beyond are fine.
Can first cousins from Missouri marry in another state?
Some couples marry in a state where it's legal. Whether Missouri then recognizes the marriage depends on its own law, so talk to a family lawyer first.