In 2022 The Law Offices of James L. Arrasmith had an article about cousin marriage:
In the state of California, marriage between first cousins is legally permitted, as the state’s marriage laws do not prohibit consanguineous relationships of this degree. This stance is rooted in several factors, including cultural diversity, autonomy, and the right to marry. A more in-depth exploration of these considerations follows:
Cultural diversity: California is known for its cultural diversity, and the state’s laws reflect this ethos. In numerous cultures around the world, marriages between first cousins are customary and socially accepted. By permitting such marriages, California acknowledges and respects the cultural practices of its residents, promoting an inclusive society.
Autonomy and the right to marry: The freedom to marry is considered a fundamental right, protected under the United States Constitution. By allowing first cousins to marry, California upholds the principle of individual autonomy, granting citizens the right to make personal choices about their relationships and marriages, provided that the relationship is between consenting adults.
Genetic concerns: While concerns about the potential genetic risks associated with cousin marriages exist, research suggests that the increased risk of genetic disorders in the offspring of first cousins is relatively small. In general, the risk of birth defects for children born to unrelated parents is approximately 3-4%, while the risk for first cousins is estimated to be around 5-6%. This relatively modest increase in risk is not considered significant enough to warrant legal restrictions on cousin marriages.
Precedents from other states and countries: California is not alone in permitting marriages between first cousins. Other states, such as New York and Massachusetts, also allow such marriages. Moreover, many countries around the world, including several European nations, permit marriages between first cousins, further supporting the notion that such relationships should not be legally restricted.