Michael and Maureen were both adopted, I believe.
Ronald Reagan and his first wife, Jane Wyman, had two children, daughter Maureen and an adopted son, Michael. Patti and Ron followed with second wife Nancy Davis Reagan. Born in 1941, at the height of Reagan's popularity as an actor, Maureen was part of the picture-perfect family that, in the 1930s and '40s, Warner Brothers promoted as Hollywood's wholesome face. Michael was adopted later, in 1946. At a time when joint custody was virtually unknown, the children remained with their mother after Reagan and Wyman divorced in 1949.
Michael is adopted, but I think Maureen was his and Jane Wyman's biological daughter. I always thought Maureen resembled Jane a lot. I may be wrong, though.
Maureen was the natural child of RWR and Jane Wyman. Only Michael was adopted, if I am not mistaken.
..Maureen is/was the daughter of Jane Wyman and Ronald Reagan.
..They also had a daughter that was born premature and died shortly after.
They adopted Michael as a baby.
Nancy was not previously married and had no children, except the two, Patty and Ron, she had with Ronald Reagan.