The marriage between blood relatives poses a great risk for the health and well-being of their children, as first cousins share 12.5% of the same DNA due to an identical set of grandparents. There is a wealth of data and studies which prove the harmful effects and direct link to birth defects.
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Marriage between blood cousins is rightfully banned in nations such as the United States, China, North and South Korea and other nations who have rightfully stood up and outlawed this barbaric practice. The only "benefits" to consanguineous marriage is the hoarding of assets and wealth, vastly outweighed by the biological havoc it wreaks on the innocent it affects. This issue affects all and needs direct action to be taken and requires people stop sticking their heads in the ground and face it.