You probably already have this, they married in Caroline Co. Va and had a child Larkin.
https://www.familysearch.org/search/trees#count=20&query=%2Bgivenname%3AJohn~%20%2Bsurname%3ARobinson~%20%2Bmarriage_year%3A1795-1797~%20%2Bspouse_givenname%3AElizabeth%20%2Bspouse_surname%3AHouston~&collection_id=(2 3)