There is something about middle children, especially in large families. They often struggle to define themselves. Robert Francis Kennedy was the ultimate middle child . Until shortly before his untimely death 50 years ago, he was still embarked on that struggle of self-determination.

Kennedy’s early career included working as a Senate staff member for the right-wing demagogue Sen. Joseph McCarthy . It would have been reasonable to conclude that as a young conservative, he could only move farther right as he aged.

Kennedy turned the tables on the conventional wisdom by moving — both by circumstance and by calculation — in a more liberal direction. But it was a distinctive liberalism that was shaped by his origins in a family that, despite their enormous wealth, were regarded as outsiders .

I’m a political scientist who studies American government and U.S. legislative politics and I’ve worked as an adviser to Democrats in the Senate and House. It is clear to me that Robert, much more than his older brother John, was shaped by the tribalism of Massachusetts politics in the 1950s.

From tribalism via religion to liberalism

For all of their money and efforts to cultivate the outward signs of WASP affluence, the Kennedys were scorned by the first families of Massachusetts the way any group with long-established wealth regards parvenues. And it wasn’t just their Irish heritage that placed them at the margins of elite Bay State society, it was their Catholicism .

Of all of the four Kennedy brothers, Robert was the most emphatically Catholic .

Struggling to distinguish himself in his sprawling family – all clamoring for attention from their father, Joseph P. Kennedy – Robert sought out his mother, Rose, who took her religion seriously.

Competitiveness within the family also bred in him a combativeness that could verge on harshness that he struggled, sometimes unsuccessfully, to control. He made an early enemy of Senate Democratic leader Lyndon B. Johnson , while as a junior staff member, by publicly rebuking Johnson. As a former staffer myself, I remain astonished at such boldness, even from a Kennedy.

Robert worked tirelessly to promote the political fortunes of his brother Jack, first in his campaign for the House and then, in 1952, when he challenged Henry Cabot Lodge for the U.S. Senate.

It was this campaign in which Joe McCarthy intervened to boost Jack’s candidacy. McCarthy, a Kennedy family friend, prevailed on the Republican Senate Campaign Committee to go easy on Jack and do as little as possible to help fellow Republican Lodge.

Bobby’s role as a staff member on McCarthy’s Senate subcommittee on investigations would have caused the casual observer to mark him as a rising right-winger. Added to that was his service as counsel to Sen. John McClellan’s investigation of corruption in American labor unions, and his conservative credentials were cemented.

The transformation

The change in Kennedy came with his controversial appointment as attorney general in the administration of his brother at a time of great tumult in race relations. The criticism was that the appointment smacked of nepotism and that Kennedy was unqualified for the position ; President Kennedy’s flip response was “I can’t see that it’s wrong to give him a little legal experience before he goes out to practice law.”

It was the era of the Freedom Riders , the mostly African-American young people who boarded buses to the South to challenge segregation. Their confrontation with local authorities often led to violence.

Kennedy’s initial reaction was that the disorder made the United States and his brother, the president, look bad in the eyes of the world: hardly the reaction of a bred-in-the-bone liberal. Also, his first dealings with Martin Luther King Jr. were tense . Kennedy authorized FBI surveillance of King , saying “He’s not a serious person. If the country knew what we know about King’s goings-on, he’d be finished.” King, for his part, resented having to ask Kennedy for help.

But ultimately, Kennedy’s experience dealing with the resistance of Southern governors to racial integration caused him to sympathize with the struggle for equality . He also recognized the importance to the Democratic Party of the black vote in the North, especially in presidential elections.

After his brother John’s assassination, Robert Kennedy left the Justice Department and ran for senator in New York. He won, and during this period, his embrace of the plight of minorities broadened to include Mexican farm workers in their struggle to unionize.