No, it is not illegal to marry your first cousin in Colorado. The state’s laws explicitly permit first-cousin marriages without restrictions, as confirmed by Colorado Revised Statutes § 14-2-110, which only prohibits unions between ancestors/descendants, siblings, or aunts/uncles with nieces/nephews.
Colorado’s Marriage Prohibitions
Colorado law bans specific close-kin marriages but allows first cousins to wed freely. Prohibited relationships include parent-child, grandparent-grandchild, full or half siblings, and aunt/uncle with niece/nephew (with a narrow exception for certain aboriginal customs). These rules apply regardless of blood quantum or fertility status, unlike some states with age or infertility caveats.
Bigamy is also illegal; parties must dissolve prior marriages or civil unions first. Minimum ages are 18 (or 16 with parental consent), and couples need a marriage license from a county clerk.
Legal Basis in Statute
Under C.R.S. § 14-2-110(1), only three family categories are void: (a) prior marriages/civil unions; (b) ancestor-descendant or sibling ties; (c) uncle-niece or aunt-nephew links. First cousins fall outside these, making their marriages valid and non-annullable on kinship grounds. County clerks, like El Paso County’s, publicly affirm this: “First cousins can marry in Colorado – FACT.”
Incest (sexual relations) remains a felony under C.R.S. § 18-6-301, but marriage itself carries no criminal penalty for cousins.
U.S. Context and Variations
Colorado is one of about 18 states allowing unrestricted first-cousin marriage; 24+ states ban it outright, and 8 impose limits (e.g., age 50+ or infertility in Arizona/Illinois). Pre-Civil War, it was legal everywhere; bans spread afterward. Out-of-state cousin couples sometimes wed in Colorado as a “destination.”
Health concerns drive many bans, as first-cousin offspring face 4-7% higher recessive disorder risks versus 3-4% general population. Yet Colorado prioritizes adult consent over genetics in law.
Historical and Cultural Notes
Cousin marriage has royal precedents (e.g., FDR wed his fifth cousin) and persists globally where not banned. In the U.S., it’s rare (0.2% of marriages) even where legal. Colorado’s permissive stance traces to common-law traditions emphasizing family alliances.
Adopted cousins or half-cousins face no extra hurdles if biologically first cousins.
Practical Steps to Marry
Apply at any Colorado county clerk’s office (e.g., Routt or El Paso) with ID, proof of age/single status, and $30 fee. No blood tests or waiting period required. Officiants (clergy, judges, or certified laypersons) perform ceremonies; self-solemnization is allowed. Post-2025 updates show no changes.
Potential Challenges
Social stigma persists, with media calling it “keeping it in the family.” Immigration may scrutinize cousin marriages for fraud, requiring affidavits. Genetic counseling is advisable for family planning, though not legally mandated.
SOURCES:
- https://www.graham.law/blog/marry-your-cousin-colorado-family-marriage/
- https://www.co.routt.co.us/328/Prohibited-Marriages
