Is it legal in every state?
Yes. Every US state and Washington, DC allow second cousins to marry. Even the strictest states only ban marriage between people "nearer of kin than second cousins" (Kentucky and Ohio use that wording), which by definition leaves second cousins allowed.
The rules people argue about are for first cousins: legal in 17 states and DC, legal with conditions in 6, and banned in 27. See the first-cousin map.
| Relationship | Can you marry in the US? |
|---|---|
| Second cousin | Yes, in all 50 states and DC |
| Second cousin once removed | Yes, everywhere |
| Third cousin and beyond | Yes, everywhere |
| First cousin once removed | Most states. A few that ban "nearer than second cousins" may include it |
| First cousin | Depends on the state |
What about other countries?
Second-cousin marriage is legal in the UK, Canada, Australia and nearly every other country; most of them allow first cousins too. One exception worth knowing: in India, the Hindu Marriage Act bans marriage between sapindas, which counts five generations on the father's side. Second cousins related through their fathers' lines can fall inside that limit, so they may not be able to marry unless a community custom allows it. Second cousins linked through a mother's side generally fall outside it. How the sapinda rule works.
How related are second cousins?
Second cousins share a set of great-grandparents: your parent and their parent are first cousins. On average you share about 3% of your DNA, around 229 cM, anywhere from about 41 to 592 cM. Your DNA test will usually list them as "2nd to 3rd cousin." What a second cousin is, with a family tree.
Is it safe to have kids?
For second cousins the extra risk is small. Every couple has about a 2 to 3% chance of a child with a serious birth defect. For second cousins it's under one percentage point higher. For comparison, first cousins add about 1.7 to 2.8 percentage points.
The risk that matters for any couple, related or not, is whether you both carry the same hidden recessive condition. About 1 in 50 couples screened on a large panel do. A carrier screen answers that for the two of you, and the carrier odds calculator shows the common conditions for your ancestry.
One caveat: if your families have married within the same community or among relatives for generations, you may be more related than "second cousin" suggests. A DNA comparison shows how much you actually share.
Is it weird?
Many people meet a second cousin as adults without knowing, especially in big families, small towns and close-knit communities. Plenty of happy, ordinary marriages are between second cousins. Legally and medically, it's a very different thing from first-cousin marriage.
General information, not legal or medical advice.