Cousin marriage has often been practised to keep cultural values intact, preserve family wealth, maintain geographic proximity, keep tradition, strengthen family ties, and maintain family structure or a closer relationship between the wife and her in-laws.

When did it stop being normal to marry your cousin?

People didnt travel far to find a spouse, and the closer you were to home, the more likely it was youd marry within your family. Then, in the late 19th century, something changed, and people stopped marrying their cousins.

Why did Royalty marry their cousins?

Marriage between dynasties could serve to initiate, reinforce or guarantee peace between nations. Alternatively, kinship by marriage could secure an alliance between two dynasties which sought to reduce the sense of threat from or to initiate aggression against the realm of a third dynasty.