Even without Father’s Day approaching later this month, it would be hard to escape the feeling that fathers are playing an outsized role in this year’s presidential race.

Senator Rand Paul is in the headlines for forcing an expiration of some provisions of the Patriot Act, a law that his father, Ron Paul, voted against as a congressman in 2001. The incumbent, Barack Obama, was elected in part on the basis of a bestselling pre-presidential memoir titled “Dreams From My Father.”

Perhaps the most intriguing father-son dynamic, though, involves Jeb Bush and President George H.W. Bush.

I was reminded of this recently on reading “41: A Portrait of My Father,” by George W. Bush, a book that sold reasonably well but hasn’t yet attracted the attention it deserves from the press following this year’s presidential campaign. Ostensibly a book by one president about his father, the book made me see Jeb Bush, the former Florida governor now running for president himself, in a new light.

To begin with, it reports, for example, that just months after Jeb Bush was born, his sister Robin was in New York being treated for the leukemia that eventually took her life. His parents would fly to New York and leave Jeb and George W. in Texas “with Midland friends and neighbors” who “became our surrogate parents.” Don’t expect to see Jeb Bush attacking Hillary Clinton for her “it takes a village” line.

When Robin Bush died, Jeb was seven months old, and, as George W. puts it in the book, “Mother cratered. She suffered bouts of depression that would plague her periodically.” “

Beyond the family dynamic, “41” sheds some useful insight on the personalities that still surround the Bushes. Pro-Israel Republicans wondered what James A. Baker III, who has strained relations at best with the pro-Israel community, was doing on Jeb Bush’s list of foreign policy advisers. The book includes a “Bush family photo” of Baker and George H.W. Bush “planning Dad’s first Presidential run in 1979.” George W. describes “Jimmy” as “a brilliant strategist” and “among the greatest political figures of the twentieth century.” The book also mentions that in the 2000 election, George W. “asked Jim Baker to lead my legal team in Florida.”

Anyone wondering why Jeb Bush hasn’t signed Grover Norquist’s pledge against a tax increase need only study the account in “41” of the difference between the reaction to George H.W. Bush’s 1990 tax increase and Ronald Reagan’s 1982 tax increase: “Unlike Ronald Reagan, George Bush had said, ‘Read my lips: no new taxes.’”

Just as eye-opening is the book’s account of the Bush family’s career in the Republican Party as, in essence, a series of showdowns against extremists. It started in 1952 with an in-person confrontation between Senator Prescott Bush, Republican of Connecticut — Jeb Bush’s grandfather — and the Red-baiting Senator Joseph McCarthy of Wisconsin. Prescott Bush denounced McCarthy’s methods and rejected a campaign contribution from him, “41” recounts admiringly.

As chair of the Harris County Republican Party in Texas in the early 1960s, George H.W. Bush eventually purged members of the extremist John Birch Society, “41” reports. George H.W. Bush lost a U.S. Senate race in Texas in 1964 when Barry Goldwater was at the top of the Republican ticket. In 1968, as a congressman, George H.W. Bush voted for the Fair Housing Act outlawing racial discrimination in housing and was greeted by constituents, the book says, “with catcalls and boos, much like the reaction when Prescott Bush had denounced McCarthy.”

George H.W. Bush was also damaged in 1992 by a challenge from Patrick Buchanan. George W. Bush writes that the Buchanan message “reminded me of the Texas far-right movement that I had encountered in the 1960s and 1970s, and it was a forerunner of today’s Tea Party.”

Jeb Bush was president of the George H.W. Bush library foundation. Last week, Jeb had an email fundraising campaign stressing the family connection: “win a signed photo of me and my dad.”

As part of the fundraising campaign, there was even an email signed George H.W. Bush: “When Jeb asked me to sign a photo of the two of us, I was all in. My only disappointment was we didn’t have one of us skydiving…but the family photo of us on the tennis court is great. Not many folks know that Jeb played tennis for the University of Texas Longhorns. Like all Bushes, he’s competitive! Maybe I’ll talk him into a parachute jump soon.”

A political father can be a hindrance as well as a help. “It’s not the Pope, it’s the pop,” was what skeptics said about John Kennedy, a Catholic whose dad was Franklin Roosevelt’s SEC chairman and ambassador to Britain. JFK was an admirer of John Quincy Adams, himself a reminder that political fathers and sons go back a long way in American history.

John Adams never sent emails offering signed photos of himself with John Quincy in exchange for political action committee contributions. If there had been emails, photos, or political action committees 200 years ago, maybe he would have. One truth that transcends both time and technology is that the father-son relationship is strong.

Mr. Stoll is editor of FutureOfCapitalism.com.