Does a person get their blood from both parents or just one?
My parents seem to think that one's blood comes only from their father. They plan on marrying me off to my first cousin (my mother's nephew; her sister's son) -- as is a custom in many Middle Eastern traditions -- and they say there would be no harm to a child born to us (no birth defects, mental retardation, etc).
I read a few reports that suggest the likelihood of birth defects in children born from consanguineous cousin-unions to be about 2% higher than children born to non-related couples. Furthermore, I don't believe that blood only comes from the father; I have reason to believe it comes from both parents.
So, if you could explain it to me in a scientific way, to dispel the myth, so that I can explain that to my parents, it would be extremely appreciated.
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