Gay civil unions exist in Denmark, Norway and several other European nations. In the U.S., attempts by gays to get a marriage license date back at least to the early 1970s.

In parts of Ancient Greece, first-cousin marriage was not only allowed but encouraged, DNA shows If you wanted to hang on to your land in Bronze Age Greece, you could do worse than marry your cousin.

The marriage of the future British queen and her consort was part of an ancient tapestry of royal intermarriage in Europe.

European law does not require countries to grant same-sex couples the right to marry, even if some states have already done so, the continent's top human rights court has ruled.

“We can completely see the cousin to cousin marriage from the genomic evidence. It’s too many people doing it to say it’s pure chance — but it isn’t 100%.

By Lianne Kolirin, CNN If you wanted to hang on to your land in Bronze Age Greece, you could do worse than marry your cousin. A team of international researchers analyzing the genomes of ancient ...