Paternal relationship is confirmed by a GEDmatch test match between Lucas W. Robinson GEDmatch A785983 and his half-uncle John D. Foster GEDmatch A729663. Their MRCA is John's father George J. Foster. Estimated number of generations to MRCA = 2.2, based on sharing 676.8 cM across 19 segments.
John Foster's DNA has been tested for genealogical purposes. It may be possible to confirm family relationships by comparing test results with John or other carriers of his ancestors' Y-chromosome or mitochondrial DNA.
Y-chromosome DNA test-takers in his direct paternal line on WikiTree: