Sweden's parliament has approved a historic law that will prohibit marriages between cousins and several other close relatives. The reform will take effect on July 1, 2026. Republicans and liberal parties reached a compromise after the government had a long deliberation on forced marriages, family pressure and honour-based violence within rigid, tightly controlled family structures.

The new constitutional amendment is primarily aimed at safeguarding individual freedom, especially for young women who may be forced to marry by their relatives. Policymakers believe that cousin marriages are a tool by which families can reinforce social isolation and tightly controlled families.

The new law was passed with unanimous support in the Swedish Riksdag and has supporters in almost every party, including the anti-immigration Sweden Democrats.

What exactly do the new laws mean for marital relationships in Sweden?

With the new law placed into effect, cousin marriages will become completely illegal in Sweden. The amending law will also prevent Sweden from recognizing cousin marriages in general conducted abroad after July 1, 2026.

The new legislation is not only about cousin marriage but also eliminates marriages between half-siblings, adopted siblings and a number of other close relatives that have previously been given some leeway until now, according to the government.

Marriages that have already been conducted and registered before July 1, 2026 will not be affected, as the Swedish government chose not to invalidate existing marriages as this could bring about legal implications.

Did health concerns play a role in the decision?

Adolescent married to an equal cousin, good genes? Public discussions of cousin marriage often touch on the risk of hereditary genetic disorders when close relatives marry. That is not the Swedish authorities' main reason to ban cousin marriage.

People also worry about social control and gender equality, as officials pointed out. The government said forced marriage and honour-related oppression can weaken personal freedom and make it difficult for families, especially women, to marry out of spite or want.

A politically sensitive issue in Sweden

The controversy about cousin marriages now forms part of a wider national debate on immigration and integration in Sweden, with authorities claiming that some tight-knit communities still arrange marriages or pressure the young to marry. The government said cousin marriages can be "the chief outlet of the logic of control and oppression".