No special conditions.
One generation apart, half the shared DNA of first cousins.
Allowed in Colorado and every other US state.
Neighboring states.
Cousin marriage laws change at the state line. Here's how Colorado's neighbors handle first cousins.
| State | First cousins | Details |
|---|---|---|
| Wyoming | Banned | |
| Nebraska | Banned | |
| Kansas | Banned | |
| Oklahoma | Banned | Also a criminal offense. |
| New Mexico | Legal | |
| Arizona | Legal with conditions | Only if both are 65 or older, or one of you can't have children. |
| Utah | Legal with conditions | Only if both are 65 or older, or 55 or older and unable to have children. |
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.
Colorado cousin questions.
Can you marry your first cousin in Colorado?
Yes. Colorado allows first cousins to marry with no special conditions.
Can you marry your second cousin in Colorado?
Yes. Second cousins can legally marry in Colorado, as in every US state.
Can you marry your first cousin once removed in Colorado?
Yes. If first cousins can marry in Colorado, so can first cousins once removed.
Is it legal to date your cousin in Colorado?
Dating isn't regulated, but marriage and incest laws can apply to close relatives. In Colorado, first cousins can legally marry. Second cousins and beyond are fine.