Analysis by Z. Byron Wolf, CNN

(CNN) -- Family loyalty is a key theme in Donald Trump's business life and political career.

White House staffers come and go at an increasingly chaotic pace, but the President's trusted direct family members seem here to stay. They either quietly work on his behalf in the White House, like his daughter Ivanka and her husband Jared Kushner. Or they loudly have his back, like his sons Eric and Donald Jr., who are steering the family business.

But the Trump era is putting plenty of tension on other Republican families.

Take the Romneys, for example.

Mitt Romney's bold declaration of independence from Trump, issued in a Washington Post op-ed, tees the former presidential candidate and new senator as either the new leader of Trump-skeptical Republicans or the last gasp of resistance to the President within his own party.

Romney didn't exactly say he was opposing Trump on any specific thing, but rather publicly registered his disappointment that Trump hasn't risen to the mantle of the presidency and put everyone on notice that he would be speaking his mind in the future. It wasn't exactly a new thought -- Romney actively tried to sabotage Trump's campaign in 2016 -- but it did offer new evidence of Trump's divisive presidency splintering Republican family allegiances.

Shortly after Trump predictably rounded on Romney on Twitter, the chairwoman of the GOP, Ronna McDaniel, joined in with a tweet of her own.

"POTUS is attacked and obstructed by the MSM media and Democrats 24/7. For an incoming Republican freshman senator to attack @realdonaldtrump as their first act feeds into what the Democrats and media want and is disappointing and unproductive."

That's a stiff rebuke for a new senator from the party's chairwoman, but it's even stiffer when you consider that McDaniel used to be known professionally as Ronna Romney McDaniel. She's Mitt Romney's niece.

McDaniel is the daughter of Mitt Romney's older brother and is from the Michigan side of the family. She went by Romney for years -- it still has cache in Michigan -- until taking over her role at the GOP, at which point she dropped the Romney and just went by McDaniel.

And part of her job as party chair is to keep the party united, even as her uncle is actively stepping into the role of public Trump critic.

That loyalty to Trump should come between an uncle and a niece is not exactly the most surprising thing in the world -- as plenty of Americans probably found in conversation with uncles over the holidays.

And this Romney-McDaniel split is nothing compared to the political divide between Kellyanne Conaway, a top presidential adviser, and George Conway, a vehement presidential critic. Those two are married, but somehow he has very publicly attacked his wife's boss on Twitter and actively worked against the presidential agenda his wife is trying to help sell.

The family divides of the Trump era are large and small, and they are visible all over the country. White House adviser Stephen Miller's uncle called his nephew an immigration hypocrite. The son (Bobby Goodlatte) of a retiring Republican congressman (Bob Goodlatte) publicly apologized for his father's role in hearings that questioned FBI agent Peter Strzok, who was involved in the Russia investigation and gave the maximum legal contribution to the Democrat running to replace his father.

Those are very public family feuds, but some of the more interesting ones have been outwardly quiet, but must have included some internal frustrations.

A large part of Trump's political identity is his criticism of past presidents, especially George W. Bush and, to a lesser extent, George H.W. Bush. Trump excessively insulted Jeb Bush during the 2016 Republican presidential primary, which Trump won and Bush lost.

That didn't stop Jeb Bush's son George P. Bush from endorsing Trump in 2016 or from seeking out Trump's endorsement for his re-election last year as Texas land commissioner. Jeb Bush kept up his criticism of Trump, however, which led Trump's son, Donald Trump Jr., to pull out of a fundraiser he had been planning to attend for the younger Bush.

George P. Bush was asked on CNN during coverage of the George H.W. Bush funeral if he had forgiven Trump for all the attacks on his father.

"You know, I'm not going to lie that, you know, it hurts. It stings," Bush said. "But, you know, my grandfather, my uncle and my dad, if they taught me anything on politics, you get back up and you fight again. And so, you know, I'm focused on my job in Texas."