A History of the McLaughlin Family/Descendants of Richard Seymour of Hartford, Connecticut for Six Generations. Compiled and arranged for publication under the directions of George Dudley Seymour by Donald Lines Jacobus New Haven, Connecticut 1939
It may be possible to confirm family relationships with Medad by comparing test results with other carriers of his ancestors' Y-chromosome or mitochondrial DNA.
Y-chromosome DNA test-takers in his direct paternal line on WikiTree:
Denny Seymour :
Family Tree DNA Y-DNA Test 111 markers, haplogroup R-BY3298, FTDNA kit #108347 +
Y-Chromosome Test 419 markers, haplogroup R-Y20344