I too have been researching the Quinney line in Scotland, which, as Bob Jeffrey states in this forum, are all descended from John Quinney of the Essex Light Dragoons, but I found John Q. married a Janet Jackson in Haddington, East Lothian Scotland on 1st April 1798. They had 2 sons: GEORGE (OPR birth entry: Quiwney/OPR baptism entry: Quinzey), born 11 Jan 1805 & THOMAS JOHN (OPR entry as Quiney) born Jan 27 1807. They also had 2 daughters:JEAN (OPR entry as Queenie/ Queenzie), born 14 Nov 1801 & JUDITH (OPR entry;Queenzie), born 3 Jun 1803 Thomas John Quinney wrote a book “ Sketches of a Soldiers Life in India”, which is available to read online ( search Google Books for the Title). The start of this book gives a summary of his family life in which he states that his father is ‘a native of Essex’. This, together with the names of his children, leads me to believe that John Quinney’s family are more likely to be George Quinney & Judith Banbrick of Witham in Essex, who also had a son named Thomas.
I have more info on the Scottish line of Quinney if anyone wants it.