To summarise:
2 couples have been suggested as possible parents of George Robertson Sr.
1. Archibald Robertson and Janet Moody - had children named John Robertson (1788) and Hugh Moody Robertson (1790). No record of a child named George, but heavy coincidence of names - George Sr's first 3 sons are named George, Archibald and Hugh Moody. The birthplace is Greenock.
2. Robert Robertson and Elizabeth Buchanan - had a son named George in 1791, plus James, Robert, Isobel, James, Elizabeth, Robert and John between 1794 and 1806. The birthplace is Paisley.
We have a likely-looking marriage between George Sr and Mary Douglas in Paisley in 1819. Mary was born in 1797 (fits census data), daughter of Colin Douglas and Elizabeth Buchanan. Douglas crops up in the family as a first or second name in later generations.
So which couple do we think were George Sr's parents?
Rambler