You really do need to give more details, and be less ambiguous: who was born 1790? William or John?
Perhaps you are looking for John Sneddan & Helen Sneddan who had a son William Sneddan b 13-6-1790 bpt 20-6-1790 Barony (Glasgow) - see IGI. ScotlandsPeople will show the exact details - I suspect the child was born to 'John & Helen Sneddan' rather than the wife's maiden name being the same.
Having said that, if you check the IGI you'll see maybe the same couple previously in Alloa (two children born there to John Snadan & Helen Snadan - again, is that really her maiden name?).
I have a note of a Peter Snadon & Margaret Snadon (or maybe Shaw?) who were in Alloa or nearby having 11 children, surname variation Snadon, Snaddon and Snedden, one of whom was John Snadon bpt 19-8-1787 Alloa. They were coal miners at least one of the children coming to the Lothian coalfields. It turned out they were not related to me, so my info is incomplete.