Let me suggest a second interpretation of the 1900 census.
Ellen was not the daughter of Catherine McNamee as shown, but the daughter-in-law and the enumerator did us a whopping big favor by listing Ellen under her maiden name.
Take a look in the 1880 census transcription for Greene Co, OH, at familysearch.org. John and Catherine (age 48)McNamee are listed with four children including the eldest, Francis, age 25, and the youngest, Ellen, age 17. In 1900 widow, Catherine, age 68, is listed as head of household. Living with her is her son, Frank, 45, single. Next is a married daughter, Ellen Quinn, age 30, and 4 children.
Back in 1880 take a look at the household of Jos Quinn, b Ireland, age 50. He has a passel of about 11 children, including Ellen, age 10.
Could the married Ellen Quinn in 1900 living with Catherine McNamee, be the Ellen Quinn, dau of Jos in 1880? I suspect so.
A variation on this approach is that Ellen was the unmarried mother of the children listed in 1900 and possibly Frank was their father.
By 1910, Ellen Quinn had moved nearby to Springfield, Clark Co, OH. She is a widow, age 50, with 2 children living with her and is said to be the mother of 2 children, both living.
The Ohio birth places and Irish parents' birthplaces are consistent in all these lisings.
I suspect that Ellen Quinn was an unmarried mother of 5-7 children as shown by the 1900-1910 censuses.
It has been over 30 years since I have done research at the Greene Co courthouse. Ellen's marriage record, if married, and certainly her children's births should be recorded there. They may be on microfilm available through Family History Centers in many Mormon Churches.
Another way to resolve the inconsistencies is to find a living male line descendant of Ellen's son, Charles, and a living male line descendant of John and Catherine McNamee, and have both DNA tested. Do they match? Goto http://www.familytreedna.com/cj.asp?ftdna_ref=199http://www.familytreedna.com/cj.asp?ftdna_ref=199 and enter your the Quinn (or any other) surname in the box at the upper right to find the Quinn Surname DNA project. Currently 22 participants.
Bill Wright descendant of Samuel Calvin Quinn of Greene Co, OH