A genealogy mystery - Louisa A Bell Kreider (1856-1911)

I have spent several days trying to work out the mystery of Louisa Bell Kreider.  Louisa A Bell Kreider (1856-1911), according to her death certificate her parents were James Bell and Sarah Ann Varner.  I'm not able to verify this biological relationship with any other source documents.  The issues are:

•  Louisa is 14 years older than her nearest age sibling.  
• Her mother (Sarah Ann Varner) was shown in the 1860 census in her parents home living under her maiden name.  Her age was 20, she would have been 16 at Louisa's birth.  
• Her father (James D Bell) was shown in the 1860 census in his parents home.  His age was 22, he would have been 18 at Lousia's birth.
• James D Bell was a Union soldier in 1862.

In summary there is not enough evidence to support that Louisa is the biological daughter of James and Sarah Ann Bell.  Obviously much more investigation is needed here.