Douglass Gilbert's DNA has been tested for genealogical purposes. It may be possible to confirm family relationships by comparing test results with Douglass or other carriers of his ancestors' Y-chromosome or mitochondrial DNA.
Y-chromosome DNA test-takers in his direct paternal line on WikiTree:
Family Tree DNA Y-DNA Test 37 markers, haplogroup R-M269, FTDNA kit #747725
It is likely that these autosomal DNA test-takers will share DNA with Douglass: