Who killed the Kennedys?

In 1981, a Louis Harris survey asked people whether certain events "were the act of one individual or part of a larger conspiracy?"  The events were the assassinations of JFK, Robert Kennedy, and Martin Luther King and the attempted assassinations of Gerald Ford and Ronald Reagan (the attempt on Reagan had taken place just a few days before the survey).

A factor analysis showed a general factor of believing in a conspiracy vs. one individual (between 10 and 18 percent said they weren't sure on the questions--I put them in an intermediate category).  People who believed they were conspiracies tended to be younger, less educated, poorer, and non-white.  None of those differences are very surprising (although the effect of income was stronger than I expected), but I was interested in exploring the age differences.  Was there a clear break between generations or a gradual shift from young to old?  Unfortunately, the Harris survey didn't record exact age, just eight groups.  However, those groups fell pretty clearly into three categories:  people born in 1947 or after were most likely to believe that they were conspiracies and people born before 1932 were least likely.  People born 1932-46 were almost exactly in the middle.  Stereotypically, this was the "silent generation," but to a large extent it was also the generation that made the 1960s the 1960s.

PS.  There were also some political differences:  people who voted for Jimmy Carter were less likely to think that they were part of a conspiracy, and so were people who called themselves moderates.