Maybe there is a connection to genealogy/researching and being Rhesus Neg as so am I!
Not to be too complex-
Everybody carries two Rhesus parts and inherits one from each parent
To be positive you can receive either two positives [+ and +]
or one of each type or [+ and -]
To be negative you receive a negative part from each parent [- and -]
Two Rhesus Positive [+ and +] parents will
only have Rhesus Positive [+ and +] children
Two Rhesus Negative [- and -] parents will
only have Rhesus Negative [- and -] children
It takes a combination of parents ([- and -] and [+ and -] or [+ and -] and [+ and -]) for a combination of positive and negative sibling children
Negative mothers who are at risk of having a positive baby must be monitored to ensure that they don't reject the baby as a foreign object in the body and this is more prevalent in second and subsequent pregnancies as anti-bodies are built up against the invasion. Injections to prevent the build up of anti-bodies are usually given after the first positive baby is born.
A blood type/group is a characteristic of specific substances on the surface of red blood cells, the two most important classifications to describe blood types in humans are ABO and the Rhesus factor (Rh factor).
More stats here for whomever is interested!
