I would not be overly concerned with the MO vs. IRE on the census. I have been doing research for over 14 years and in my experience census takers are known for making errors and people often gave misinformation to the census taker for whatever reason. There have been times throughout history when it was not socially acceptable to have a particular ancestry.
Here is the child from the first marriage. This is the info from her marriage license.
Missouri Marriage Records, 1805-2002
about Ruth Hutchison
Name: Ruth Hutchison
Marriage Date: 20 Feb 1934
Marriage Location: Chillicothe, Livingston, Missouri
Marriage County: Livingston
Spouse Name: Ray Lindon Rupe
Mother's Name: Mrs. Charles Hutchison
Father's Name: Mr. Hutchison