Conversation so far:
What is important about L. Frank Baum's South Dakota years?
L. Frank Baum's description of Kansas in The Wonderful Wizard of Oz is based on his experiences in drought-ridden South Dakota
Who were L. Frank Baum's parents?
L. Frank Baum was the seventh of nine children of Cynthia Ann (née Stanton) and Benjamin Ward Baum.

Question: Did he have siblings?
Self-contained rewrite: Did L. Frank Baum have siblings?