Conversation so far:
Where was Ben Carson born?
Carson was born in Detroit, Michigan.
Does Ben Carson have siblings?
Ben Carson has an older brother, Curtis.
Where did Ben Carson attend school?
Ben Carson graduated with a B.A. in psychology from Yale and with an M.D from the University of Michigan Medical School.
Who are Ben Carson's parents?
Ben Carson was born to Robert Solomon Carson, Jr. (1914–1992), a World War II U.S. Army veteran, and his wife, Sonya Carson (née Copeland; 1928–2017).

Question: Who is his mother?
Self-contained rewrite: Who is Ben Carson's mother?