... Gaffy, I am intrigued by your possibility of another Thompson Keys and wife Mary Patterson. I suppose what I am asking is does the birth certificate I hold mean that Mary Patterson could not have been my Mary Keys mother? ...
I posted the Thompson Keys and Mary Patterson couple as possible parents to the Thompson Keys who married Martha Jane Robinson, not as parents to Mary. Just to summarise what I think, in case it wasn't clear (and yes, some of this is ultimately conjecture, but not without reasonable foundation / context of names, locations, timings etc.):
- the parents of Mary Keys born 1908 were Thompson Keys and Martha Jane Robinson who got married in 1902 - in addition to siblings William and Thompson, Mary had other siblings Lena, Joseph and Charles;
- Mary's mother, Martha Jane Robinson was born 1878 to Rhoda Robinson, father not known, Martha Jane may have had an older sister Elizabeth;
- Rhoda Robinson went on to have other children William and John Keys with Fleming Keys (can't find the Robinson-Keys marriage yet), this is one possible explanation why her earlier illegitimate daughter Martha Jane Robinson sometimes adopted the Keys surname;
- turning to Thompson Keys (father of Mary born 1908 / husband of Martha Jane Robinson), possible parents for him were Thompson Keys and Mary Patterson who got married in 1848 (the father of the Thompson Keys who married Mary Patterson in 1848 was also called Thompson Keys).
Into the mix is the possibility that the Fleming Keys with whom Rhoda Robinson had children William and John, was related to the Thompson Keys that married Rhoda's daughter Martha Jane Robinson in 1902 (possibly an Uncle?).
Rhoda (Robinson) Key's age in the 1901 and 1911 is consistent, suggesting birth c. 1865. If all of this is correct, it would mean she had daughter Martha Jane Robinson when she was 13 (and possible sister Elizabeth when 11). Notwithstanding the consistency, the age may be wrong / understated, I couldn't find a civil birth.
Just to add that I've seen the birth record for John Keys, the 12 year old in the 1901 census return for house 3, Mullaghtinny, it confirms his father as Fleming Keys and his mother as Rhoda Keys, formerly Robinson.