According to Thomas Death Certificate both his parents were born in England, unfortunately they are not named. His daughter Mary Coombs Pomeroy's transcription from New York City Municipal Deaths 1795-1949 notes that her father's birthplace is Bristol, England. This needs to be confirmed, to date I have been unable document his birth.
New York Newspaper "The Sun" April 7, 1892 Death Notice
It may be possible to confirm family relationships with Thomas by comparing test results with other carriers of his Y-chromosome or his mother's mitochondrial DNA.
However, there are no known yDNA or mtDNA test-takers in his direct paternal or maternal line.
It is likely that these autosomal DNA test-takers will share DNA with Thomas: