Hoover: In charge of US famine relief in Europe after World War I
FDR: Assistant Sec'y of the Navy, World War I
Truman: Army Captain, World War I
Ike: Well we know about him
Kennedy: PT 109 etc.
Johnson: Served in WWII
Nixon: Same
Ford Same
Carter: WWII era West Point grad, Navy officer
Reagan: Served during WWII
Bush I: Pilot, WWII
So when Kerry decided to run for president (as Gore did) when he was 11 years old, he knew that miltary service, especially in a shooting war, was a prerequiste. Getting a few medals, even better. IMO, that's the only reason he went to Vietnam.