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Can you marry
your step-sibling?

Yes, in every US state and DC except West Virginia. Step-siblings aren't related by blood, so most marriage laws don't mention them. In West Virginia, the law isn't clear. Adoptive siblings are a different story. Here's every state, checked against its statutes.

By the DontMarryYourBro team · Updated November 2026 · 6 min read · How we fact-check

The short answer

  • Step-siblings: legal everywhere except West Virginia (unclear there).
  • Adoptive siblings: of the 51 jurisdictions, 11 ban it, 3 clearly allow it, and 37 don't clearly address it.
  • Watch out for step-parent adoption. If a step-parent legally adopted one of you, you may now be adoptive siblings in the eyes of the law.
  • No genetic risk from being step-siblings, because you share no family DNA.

Why step-siblings are usually allowed

Marriage laws ban close blood relatives (parents, siblings, aunts and uncles, and in some states first cousins) and sometimes a few relatives by marriage, like a step-parent. Step-siblings are related only because their parents married each other. Most states' laws don't mention them at all, which means the marriage is allowed.

A few states have broader rules about relatives by marriage, and a handful of statutes are worded in a way that leaves the answer unclear. The table below shows each one.

Step-siblings and adoptive siblings, state by state

StateStep-siblingsAdoptive siblings
AlabamaLegalNot allowed
AlaskaLegalNot clearly addressed
ArizonaLegalNot clearly addressed
ArkansasLegalNot clearly addressed
CaliforniaLegalNot clearly addressed
ColoradoLegalLegal
ConnecticutLegalNot clearly addressed
DelawareLegalNot allowed
Washington, DCLegalNot clearly addressed
FloridaLegalNot clearly addressed
GeorgiaLegalNot clearly addressed
HawaiiLegalNot clearly addressed
IdahoLegalNot clearly addressed
IllinoisLegalNot allowed
IndianaLegalNot clearly addressed
IowaLegalNot clearly addressed
KansasLegalNot clearly addressed
KentuckyLegalNot clearly addressed
LouisianaLegalNot allowed
MaineLegalNot clearly addressed
MarylandLegalNot clearly addressed
MassachusettsLegalLegal
MichiganLegalNot clearly addressed
MinnesotaLegalNot allowed
MississippiLegalNot clearly addressed
MissouriLegalNot clearly addressed
MontanaLegalNot clearly addressed
NebraskaLegalNot clearly addressed
NevadaLegalNot clearly addressed
New HampshireLegalNot clearly addressed
New JerseyLegalNot clearly addressed
New MexicoLegalNot clearly addressed
New YorkLegalNot clearly addressed
North CarolinaLegalNot clearly addressed
North DakotaLegalNot clearly addressed
OhioLegalNot clearly addressed
OklahomaLegalNot clearly addressed
OregonLegalNot allowed
PennsylvaniaLegalNot clearly addressed
Rhode IslandLegalNot clearly addressed
South CarolinaLegalNot clearly addressed
South DakotaLegalNot allowed
TennesseeLegalNot allowed
TexasLegalNot allowed
UtahLegalNot clearly addressed
VermontLegalNot clearly addressed
VirginiaLegalNot allowed
WashingtonLegalNot clearly addressed
West VirginiaNot clearly addressedNot allowed
WisconsinLegalNot clearly addressed
WyomingLegalLegal

"Not clearly addressed" means the statute doesn't settle it either way. Checked against each state's marriage and incest statutes in November 2026. Laws change, so confirm with your county clerk. Click a state for its full page, including in-laws and step-parents.

The step-parent adoption catch

If your step-parent legally adopted you, or your parent adopted your step-sibling, you're no longer just step-siblings: you're adoptive siblings. Several states treat adoptive relationships like blood ones for marriage, and many more don't address it clearly. If an adoption happened in your blended family, check before you plan a wedding.

What about the genetics?

Step-siblings share no family DNA, so there's no extra genetic risk from the relationship itself. The same is true of adoptive siblings who aren't biologically related. The usual checks still apply, like a carrier screen before pregnancy, which every couple can benefit from.

Not sure if you're biologically related at all? In blended families, donor-conceived families and adoptions, it's more common than people think. A DNA relatedness check settles it.

Outside the US

Step-siblings and adoptive siblings can marry in England and Wales. Who you can marry in the UK. In India, step-siblings aren't within the prohibited degrees under Hindu, Muslim or civil marriage law. The India relationship checker.

General information, not legal advice. For your situation, talk to a family lawyer.

Blended family? Know for sure.

If you're not certain you're unrelated, a free DNA check compares your DNA in your browser, in seconds.

Check if we're related

Questions people ask.

Is it legal to marry your step-sibling?

Yes, in every US state and DC except West Virginia. In West Virginia, the law isn't clear. Step-siblings aren't related by blood, so most state laws don't prohibit it.

Can you marry your adopted sibling?

It depends on the state. 11 jurisdictions explicitly ban it, 3 explicitly allow it, and 37 don't clearly address it. Check your state before planning anything.

Is dating your step-sibling illegal?

Dating isn't regulated by marriage law. If one of you is a minor, or if a step-parent adoption made you adoptive siblings, other laws can apply, so be careful.

Do step-siblings share DNA?

No. Step-siblings are related only through their parents' marriage and share no family DNA, so there is no added genetic risk from the relationship.

Can you marry your step-sister in the UK?

Yes. Step-siblings and adoptive siblings are not within the prohibited degrees in England and Wales.