Just to explain further .. the birthplace for Sarah clearly states Doddington in 1891. In 1851 the birthplace for the claimed unmarried daughter of James .. and sister to John is also Doddington.

I would hazard a guess the 1851 census should read dau in law .. but I haven't been able to find a marriage as yet .. ?
Referring to the above, neither can I find a birth for Sarah .. here are the others, mostly as listed in 1841 and 1851 .. children of James and Mary:
Birth, 1st. February 1814
Christening, 20th February 1814
Jane FettisParents: James and Mary Fettis
Birth, 21st. January, 1817
Christening, 2nd. February, 1817
Margaret FettesParents:
James Fettes
Mary Fettes
Christening, 15th June 1823
Queeny Scott FettisParents:
James Fettis
Mary Fettis
Christening, 13th March 1826
James FettisParents:
James Fettis
Mary Allen
Christening, 19th July 1829
John FettisParents:
James Fettis
Mary Allen
Christening, 8th January 1832
Ann FettisParents:
James Fettis
Mary Allen
Christening, 29th March 1835
Death, 28th September 1848
Mary FettisParents:
James Fettis
Mary Allen