Marrying a cousin raises questions about legality across U.S. states, with New Hampshire standing out in New England. State laws clearly prohibit first-cousin marriages here, though nuances exist for other relatives.
New Hampshire’s Marriage Prohibitions
New Hampshire law bans marriage between first cousins related by blood or closer lineage. The Town of Exeter’s official guidelines state: “Marriage is not permitted in New Hampshire between people who are related by blood as first cousins or in any more direct lineage.” This makes New Hampshire the only New England state with such a restriction, unlike Massachusetts or Maine, which allow it.
The prohibition targets direct blood relations to prevent genetic risks in offspring. First cousins once removed can marry, but adopted cousins face the same ban as blood relatives. Violations invalidate the marriage license application at town or city halls statewide.
Standard Marriage Requirements
Beyond kinship rules, couples must meet age and consent thresholds. Parties need to be 18 or older without parental approval; 16-17-year-olds require it. A marriage license, obtained locally, demands identification, fees, and a waiting period in some cases.​
Clerks verify no prohibited relationships during application. Ceremonies must occur post-licensing, with the signed document returned promptly. Common-law marriages from other states may be recognized, but new ones aren’t formed in New Hampshire.​
Why the Cousin Ban Exists
Concerns over genetic disorders drive these laws, as first cousins share about 12.5% DNA, raising recessive trait risks fourfold compared to unrelated pairs. New Hampshire prioritizes public health, aligning with 25 states fully banning first-cousin unions.
Social stigma also factors in, though living together or relations aren’t criminalized. Critics argue risks are overstated—lifetime child defect rates hover at 4-7% for cousins—but states like New Hampshire maintain firm lines.
Comparisons with Neighboring States
This table highlights regional variance, with New Hampshire most restrictive.​
Health and Social Considerations
Couples eyeing cousin marriage often seek counseling. Genetic testing reveals carrier status for conditions like cystic fibrosis. Culturally, it’s accepted in parts of the Middle East or South Asia but taboo in the U.S. West.​
Legally, out-of-state cousin marriages may hold if valid elsewhere, per full faith and credit. However, New Hampshire won’t issue licenses violating its code.​
Sources
- (https://wjbq.com/ixp/701/p/is-it-illegal-to-marry-your-first-cousin-in-new-england/
- https://shark1053.com/ixp/701/p/is-it-illegal-to-marry-your-first-cousin-in-new-england/
- (https://collincountymagazine.com/2025/07/04/is-it-illegal-to-marry-your-cousin-in-new-hampshire-heres-what-the-law-says
