Dating your step-cousin is legal everywhere in the United States. Step-cousins are connected only through a parent’s marriage, not by blood, so they sit outside the incest and prohibited-kinship laws that restrict relationships between close biological relatives. The complications that come up are usually social, with one legal exception worth knowing about: a formal adoption somewhere in the family tree can change the analysis.
Why Step-Cousins Aren’t Covered by Incest Laws
Family law separates two kinds of relationships. Consanguinity means shared blood. Affinity means connection through marriage. Incest statutes target consanguinity, because their purpose is to prevent genetic harm to offspring. A step-cousin relationship is pure affinity, so those laws don’t reach it.
The scope of incest laws is also narrower than most people assume. Criminal incest provisions across the country focus on close blood relatives: parents and children, grandparents and grandchildren, siblings, and sometimes aunts, uncles, nieces, and nephews.1Legal Information Institute. Incest The Model Penal Code, which shaped many state statutes, limits the offense to “an ancestor or descendant, a brother or sister of the whole or half blood, or an uncle, aunt, nephew or niece of the whole blood.” Cousins don’t appear on that list at all. Step-cousins are several degrees further removed, and no state has passed a law specifically prohibiting romantic or sexual relationships between them.
Age of Consent Is the Only Criminal Concern
If both people are legal adults, there is no criminal liability attached to the relationship. The family link through marriage doesn’t fall within any prohibited-relationship statute, so prosecutors have nothing to work with.
The one criminal issue is the same one that applies to any couple: age of consent. That threshold ranges from 16 to 18 depending on the state, with most states setting it at 16. A relationship where one person is below the applicable age can result in serious felony charges, and family status doesn’t change that. What matters is that both people are above the age of consent in your state.
Can Step-Cousins Get Married?
Yes. Marriage between step-cousins is permitted in every U.S. jurisdiction. When a couple applies for a marriage license, the clerk checks whether the applicants fall within the state’s prohibited degrees of kinship. Those prohibitions cover direct-line relatives, siblings, and in most states, aunts, uncles, nieces, and nephews. Step-cousins don’t appear on any state’s restricted list.
For context, even biological first cousins can legally marry in roughly 20 states. Step-cousins, who share no genetic connection at all, face no marriage restrictions anywhere in the country. The application process is the same as for any other couple, and no jurisdiction requires genetic testing or a blood-relationship review for step-cousin applicants.
When Adoption Changes the Answer
This is the one scenario where a step-cousin relationship can become legally complicated. When a stepparent formally adopts a child, the law treats that child as the biological offspring of the adoptive parent. The legal effect ripples outward through the family tree. A step-cousin who was previously connected only through marriage may become a legal cousin through the adoption decree.
The Model Penal Code explicitly extends its incest provision to a “relationship of parent and child by adoption,” and many states follow that approach for other adoptive relationships as well. If the adoption creates a legal relationship that falls within a state’s prohibited degrees of kinship, the couple could face barriers to marriage or even criminal liability for a sexual relationship. A marriage entered in violation of these prohibitions would likely be void from the start, meaning it was never legally valid, rather than merely voidable.
The practical point: if either person in the relationship was legally adopted by a relative on the other side of the blended family, check whether that adoption moved the relationship into prohibited territory under your state’s law. The specific adoption decree matters more than the general rule, and a short consultation with a family law attorney can settle it.
What Happens If the Connecting Marriage Ends
Step-cousin relationships exist because two families were joined by marriage. If that marriage ends through divorce or death, the traditional legal rule is that affinity relationships dissolve with it, unless children were born from that marriage.
In practical terms, if your parent divorces the spouse whose family includes your step-cousin, the two of you may no longer be step-cousins in any legal sense. The relationship was already legal while the marriage existed. Once the marriage dissolves, the already-weak legal connection disappears entirely.
Inheritance Doesn’t Follow the Step-Cousin Link
Where the step-cousin relationship does create real limits is in inheritance. If someone dies without a will, their property passes through intestate succession, a hierarchy that prioritizes spouses, children, parents, siblings, and then progressively more distant blood relatives. Step-relatives, including step-cousins, are generally invisible to these default rules. Most states define heirs through blood or legal adoption, not through the marriage that created a step-relationship.
If you’re in a relationship with a step-cousin and either of you wants the other to inherit property, put a will or trust in place. Intestate succession will not do the work. This applies equally to step-cousins who are dating and those who are married; the marriage itself would create spousal inheritance rights, but the underlying step-cousin connection does not.
Workplace Anti-Nepotism Rules
Some employers, particularly government agencies, restrict relatives from working in the same chain of command. The federal anti-nepotism statute defines “relative” to include step-parents, step-children, step-siblings, half-siblings, first cousins, and in-laws, but it does not include step-cousins.2Office of the Law Revision Counsel. 5 US Code 3110 – Employment of Relatives; Restrictions A step-cousin relationship falls outside the scope of that federal restriction.
Private employers set their own policies, and some cast a wider net. A company fraternization or anti-nepotism policy may define “family member” broadly enough to capture step-cousins, especially if it uses open-ended language like “any relative by blood or marriage.” If you and a step-cousin work for the same employer, read the employee handbook rather than assuming you’re in the clear.