Who were the parents of Mary Ann Stephens in Kenwyn, Cornwall, 1841 and 1851 Censuses?
Research note by Wesley Johnston, begun 14 May 2014, last updated 14 May 2014
 
Background
The widow Ann (Sandoe) Stephens appears with Mary Ann Stephens in the 1841 and 1851 censuses of Kenwyn, Cornwall. Here are the links to these images in Ancestry:
1841 - http://interactive.ancestry.com/8978/CONHO107_147_147-0090
1851 p 1 of 2 - http://interactive.ancestry.com/8860/CONHO107_1910_1910-0981
1851 p 2 of 2 - http://interactive.ancestry.com/8860/CONHO107_1910_1910-0982
In the 1851 census, Mary Ann's birth place is shown as Kenwyn. She is the niece and Ann the sister-in-law of the head of the house, who is Ann's sister Mary's husband.
In 1851, she is shown as age 24 (thus born about 1827). In 1841, she is shown with age 15, which may be rounded to the nearest 5 years, since that is what was done in the 1841 census.
So who were the parents of Mary Ann Stephens?
Candidate Mary Ann Stephens Baptisms
The Cornwall Family History Society research database of baptisms shows four possible candidates for Mary Ann at Kenwyn, showing the abode at the end of each entry:
-- 1826 Feb 20 - Mary, base child of Elizabeth STEPHANS == https://familysearch.org/pal:/MM9.3.1/TH-266-11775-52638-68 >> Truro
-- 1826 Jun 26 - Mary Ann Amelia, base child of Ann STEPHENS== https://familysearch.org/pal:/MM9.3.1/TH-266-11775-59862-98 >> Calenick Street
-- 1827 Jan 1 - Mary Ann, daughter of Samuel and Dinah STEPHENS == https://familysearch.org/pal:/MM9.3.1/TH-266-11775-60293-84 >> Pyder Street in Truro
-- 1828 Mar 6 - Mary Ann, daughter of Hercules and Jane STEVENS == https://familysearch.org/pal:/MM9.3.1/TH-266-11775-54185-76 >> Charles Street
None of these appear in the Kenwyn burials up to 1837.
Calenick Street appears in connection with Ann (Sandoe) Stephens and with Mary Ann Stephens in other records. They are together in the 1841 Census on Calenick Street. Ann's daughter Harriet Ann Stephens died on Calenick Street in 1833.
Thus the evidence most closely fits Ann (Sandoe) Stephens as the mother of Mary Ann.