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Dr. Chip
Dr. Chip, Board Certified Physician
Category: Medical
Satisfied Customers: 31218
Experience:  20 yrs. in practice, includinge surgery, general medicine, addiction medicine and pain.
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Its a paternity question. My parents both have rhesus negative

Resolved Question:

Its a paternity question. My parents both have rhesus negative blood groups me and my older sister have positive. We know that this is not possible. But if my sister's biological dad was rhesus positive could this have contaminated my mum's blood resulting in me being my dad's daughter?
Submitted: 2 years ago.
Category: Medical
Expert:  Dr. Chip replied 2 years ago.

Hi--just to be clear here are you saying your sister and you have two different dads?

Customer: replied 2 years ago.

We have been raised to believe that our dad is both our dad, but we found out last year about the blood groups due to my nephew being unwell. So we thought that she, being the eldest could have a different dad with rhesus positive and that when our mum carried her it somehow contaminated her blood meaning I could be my dad's, the one who is rhesus negative.

Expert:  Dr. Chip replied 2 years ago.
OK. Basically if both parents are rH negative, their children will all be rH negative. And if an rH positive man mates with an rH negative woman, that doesn't contaminate her blood--if she had a second child from an rH negative man, that child would still be rH negative
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