There is an Alexander Keith Hutcheon, b. 19 Nov 1870, Millbrex, Aberdeenshire to Jane Hutcheon - only the mother is named on the birth registration, which suggests he was, indeed, illegitimate, but the record on SP will confirm that.
This appears to be the family in 1871 in Millbrex:
Jane Fowlie, head, unmarried, 49, worsted knitter, New Deer
William Hutcheon, son, unmarried, 26, shoemaker, New Deer
Jane Hutcheon, daughter, unmarried, 19, dressmaker, New Deer
Alexander K Hutcheon, grandson, 4 months, Millbrex
And here is Jane with her family in 1861 in New Deer - it seems likely that Jane herself was also illegitimate, as her mother, Jean Fowlie is shown as unmarried.
Jean Greig, head, widow, 85, crofter’s widow, New Deer
Jean Fowlie, servant, unmarried, 38, sick nurse, New Deer
William Hutcheon, visitor, unmarried, 16, shoemaker apprentice, New Deer
Jean Hutcheon, boarder, 9, scholar, New Deer
I can then see Jane as a nurse in 1881, 1891 and 1901:
1881 at the Poor House in New Deer - I suspect this is her, despite her place of birth being Monquhitter and not New Deer as in the other censuses:
Jane Hutcheon, field worker, aged 29, Monquhitter
1891 at Buchan Poorhouse, New Deer
Jane Hutcheon, nurse, aged 38, New Deer
1901 at Old Deer Hospital
Jane Hutcheon, nurse, aged 49, New Deer
Ruth