First-cousin marriage is void.
Closer than second cousins, so it falls under the ban.
Allowed in Ohio and every other US state.
Neighboring states.
Cousin marriage laws change at the state line. Here's how Ohio's neighbors handle first cousins.
| State | First cousins | Details |
|---|---|---|
| Michigan | Banned | |
| Indiana | Legal with conditions | Only if both are 65 or older. |
| Kentucky | Banned | Bans marriage "nearer of kin than second cousins," and doesn't recognize ones from other states. |
| West Virginia | Banned | |
| Pennsylvania | 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.
Ohio cousin questions.
Can you marry your first cousin in Ohio?
No. Ohio only allows marriage between people who are not nearer of kin than second cousins, so first cousins cannot marry there.
Can you marry your second cousin in Ohio?
Yes. Second cousins can legally marry in Ohio, as in every US state.
Can you marry your first cousin once removed in Ohio?
No. Ohio bans marriage between people nearer of kin than second cousins, and a first cousin once removed is closer than a second cousin.
Is it legal to date your cousin in Ohio?
Dating isn't regulated, but marriage and incest laws can apply to close relatives. In Ohio, first cousins can't legally marry, so a serious relationship can become legally complicated. Second cousins and beyond are fine.
Can first cousins from Ohio marry in another state?
Some couples marry in a state where it's legal. Whether Ohio then recognizes the marriage depends on its own law, so talk to a family lawyer first.