Brief Answer: As below. Detailed Answer: Hi, Welcome to Healthcare Magic! If your son is sure about his blood group being O, then there is no need to know your blood group. If both parents have the O blood group then it is highly unlikely that the child can have a blood group other than O. I expect there has been some mistake and probably either your son or daughter in law does not have O blood group. Please also note that blood grouping cannot confirm or refute paternity as in some very rare situations, the usual rules of inheritance are not followed. I know you would like to cross-check this information. So I am including a few links for you. Check this site which very clearly explains in simple terms what a child's group can be if the parents' blood groups are known: WWW.WWWW.WW au/blood_basics/blood_groups/inheritance_patterns There are a few other sites where you an find the same information, though not so simply explained: WWW.WWWW.WW WWW.WWWW.WW WWW.WWWW.WW Please do not let this information unduly worry you or your son. Many times people have incorrect knowledge of their own blood types. There is no harm in testing the blood groups again before jumping to any conclusions. Best wishes. Dr Preeti Parakh MD Psychiatry

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