Robert F. Kennedy Jr.’s declaration that his father and uncle would feel more at home in President Trump’s GOP is a stunning admission from a scion of the family. It came in a conversation between RFK Jr. and our publisher, Dovid Efune. The erstwhile candidate for president now endorses Trump, and has joined his transition team. His forebears, he reckons, would not “have a place in today’s Democratic Party.” Call it a cri de coeur from Camelot.

“All the policies that my uncle and father believed [in], and I believe I would check every one of those boxes, and Donald Trump today is much closer to that, and he doesn’t agree with me on everything,” RFK Jr. told Mr. Efune. Mr. Kennedy remembers when Democrats “were always the anti-war party, we were the party of civil rights and constitutional rights, including freedom of speech.” Now he calls Democrats the “party of censorship and surveillance.”

No doubt RFK Jr.’s version of this story is somewhat self-serving. It was, after all, the Democrats — starting with his uncle — who took us into Vietnam. It was RFK Jr.’s father who broke with the legacy of his own brother and did so much to turn the Democratic party away from the war. “Last Days in Vietnam,” a courageous and devastating documentary produced by RFK Jr.’s sister, Rory, plumbs this drama.

RFK Jr.’s account of what he calls a “complete inversion” between the parties is, in any event, bitterly contested by his relatives, who have lined up behind President Biden and now Vice President Harris. One statement avers that “our brother Bobby’s decision to endorse Trump today is a betrayal of the values that our father and our family hold most dear. It is a sad ending to a sad story.” Yet the erstwhile candidate cites “principled causes” for his decision.

RFK Jr. shared some of those causes during his conversation with Mr. Efune. They include the Biden-Harris administration’s support for changes to Title IX — legislation championed by Senator Ted Kennedy  — that RFK Jr. claims will harm women. He accuses the Democrats of being “against women’s sports and all of these different issues.” He also recalls that the “Democratic Party that I grew up with was the party of peace.”

We understand that RFK Jr.’s passel of eccentricities will not be to everyone’s taste — or recollection. His own presidential campaign began with a bang and ended with a whimper. Still, his intimations of realignment could prove prescient. These pages have noted the movement of the working class, of all races, toward Trump. Then there is the turn of many in the party of President Truman against Israel, of which Democrats were once stalwart.

It could be that RFK Jr. grasps something of the nature of his family’s political bequest that others have missed. Our columnist Ira Stoll wrote a whole book called “JFK, Conservative,” wherein he argues that the quintessential Democrat’s commitment to fighting communism and midwifing growth through supply-side tax cuts mark him as a conservative. Another of our columnists, Larry Kudlow, wrote a book comparing the JFK fisc to Reagan’s.

In any event, the inheritance of the Democrats is well within bounds as Vice President Harris, who won no primary votes, seeks to gain the White House despite a record of policy positions that could have been written on an Etch-a-Sketch. Much ink has been spilled over Trump’s departure from Republican bedrock. RFK Jr., though, is prompting a conversation over whether the molting of Democrats has been no less dramatic. Camelot, too, can change.