Cousin Marriage
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Marrying a cousin would be a very wrong idea, in my opinion. Because cousin is as far or close as brother. A person's cousin is still a child, an aunt's child, an uncle's child, or an uncle's child. Closeness like a sibling. Even if the child is not from your mother, it is from your mother's sister. Even if he is not from your father, your father is from his brother.
Cousin marriages occur mostly in uncivilized societies. It's also biologically dangerous. I am against cousin marriage.