It depends on which John Kerr, you are talking about:
Sir John Kerr (governor-general) (1914-1991), Australian Governor-General
John Kerr, Baron Kerr of Kinlochard (born 1942), British diplomat
John Kerr (US politician) (c. 1778-1823), Irish-born mayor of Columbus, Ohio
John Leeds Kerr (1780-1844), U.S. Senator from Maryland
John Kerr (Virginia Congressman) (1782-1842), Virginia politician
John Kerr, 7th Marquess of Lothian (1794-1841), Scottish politician and peer
John Bozman Kerr (1809-1878), U.S. Representative from Maryland
John Kerr, Jr. (congress) (1811-1879), Congressional Representative and jurist from North Carolina
John Kerr (British politician) (1852-?), UK MP for Preston, 1903-1906
Sir John Henry Kerr (1871-1934), colonial governor in British India
John H. Kerr (1873-1958), Congressman from North Carolina in the 20th century
John H. Kerr, III (born 1936), North Carolina politician
John Kerr (Nelson politician) (1830-1898), New Zealand (Nelson) politician
John Kerr (Auckland politician), New Zealand (Auckland) politician
The historical figure John Dodd, a member of Parliament, is the only semi-famous John Dodd I can find, and there is no information about his sexual orientation.
John Heileman is straight.
no.
straight
he is straight.
John D. Rockefeller Sr. never publicly discussed his sexual orientation, but it appears that he was heterosexual.
John Mahoney, best known from his role on Frazier, has not publicly stated his sexual orientation, though there are many rumours and speculation.
Isn't he gay?
John Maybury, the filmmaker, is openly gay.
John Saul is openly gay, and has been with his partner since 1982.
John Prats has never publicly discussed his sexual orientation. All we can say is that he's marred to a woman, Isabel Oli, since 2015.
John Garfield was thought to be heterosexual, and he was married to Roberta Seidman.