This is one of the biggest insult out there. It just means they don't have that rhesus line, which could be from and ancient virus or something. Truth is O- plus B- newer understanding, can father any blood type child, the mother being O- does not give the blood types the father does, they do pass on part of their extra blood group lines as their Dads or grandparent, most negatives, have some positive factors in their blood, people make mistakes thinking is just simple groupings. I have people in my family who are positive and a heck of a lot who are negative, some were in a very rare AB-with a group of factors that had only 3 known people who were able to give each other blood. All of his donors died before he did, two were in the US and one in England.