Is it okay to date your third cousin? Since third cousins share only a very small percentage of their DNA, there is no issue with third cousins dating from a genetic perspective. According to an article by The Spruce, marriage between second cousins and more distant cousins is legal throughout the United States.

How much DNA do 3rd cousins share?

We say that two individuals share DNA when both individuals inherited the same DNA from the same ancestor .Percent DNA Shared by Relationship.RelationshipAverage % DNA SharedRange2nd Cousin3.13%2.85% - 5.04%2nd Cousin once removed1.5%0.57% - 2.54%3rd Cousin0.78%0.3% - 2.0%4th Cousin0.20%0.07% - 0.5%7 more rows

Is it bad to marry your 3rd cousin?

In short, yes, it is legal for second and third cousins to marry in the US. The risk of birth defects in children born to first cousins is increased from a baseline of 3-4 percent to 4-7 percent, according to the National Society of Genetic Counselors.