First-cousin marriage is void.
The ban targets first cousins. Confirm with your county clerk.
Allowed in Idaho and every other US state.
Neighboring states.
Cousin marriage laws change at the state line. Here's how Idaho's neighbors handle first cousins.
| State | First cousins | Details |
|---|---|---|
| Washington | Banned | |
| Oregon | Banned | |
| Nevada | Banned | Also a criminal offense. |
| Utah | Legal with conditions | Only if both are 65 or older, or 55 or older and unable to have children. |
| Wyoming | Banned | |
| Montana | 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.
Idaho cousin questions.
Can you marry your first cousin in Idaho?
No. Idaho does not allow first cousins to marry.
Can you marry your second cousin in Idaho?
Yes. Second cousins can legally marry in Idaho, as in every US state.
Can you marry your first cousin once removed in Idaho?
Usually yes. Idaho's ban targets first cousins, but check the exact statute or ask your county clerk.
Is it legal to date your cousin in Idaho?
Dating isn't regulated, but marriage and incest laws can apply to close relatives. In Idaho, first cousins can't legally marry, so a serious relationship can become legally complicated. Second cousins and beyond are fine.
Can first cousins from Idaho marry in another state?
Some couples marry in a state where it's legal. Whether Idaho then recognizes the marriage depends on its own law, so talk to a family lawyer first.