In a lengthy answer in Tuesday's Republican debate about whether he agrees with Donald Trump's proposal to temporarily ban Muslim immigrants from the United States, Sen. Ted Cruz (R-Tex.) drew on a colorful metaphor from the history books to make his point.

"Well, you know, I'm reminded of what FDR's grandfather said," Cruz relayed. "He said, 'All horse thieves are Democrats, but not all Democrats are horse thieves.'"

Cruz's message was that those who wish to do America harm are Muslims, but that doesn't mean all Muslims want to hurt Americans. ("It's not a war on a faith," he added.) It was a subtle, tonal difference with Trump; Cruz has tried to buddy up with the GOP front-runner and has largely declined to directly comment on Trump's proposal.

But the man Cruz was quoting was, well, complicated.

That quote is attributed to Warren Delano, the influential (and therefore quotable) grandfather of America's 32nd president. Delano helped the Roosevelt family become the political powerhouse of the early 20th century thanks to selling drugs — opium, specifically.

At the time, Delano was on the up-and-up in a Boston shipping company that specialized in buying silk and tea from China, wrote journalist Karl Meyer in a 1997 New York Times column. In an effort to encourage a stingy China to buy some products from the West, traders such as the Boston shipping company started marketing opium — even though the drug was banned in the empire.

In his May piece for Ozy, "The drug that bankrolled some of America's great dynasties," senior writer Sean Braswell writes that breaking into the red-hot opium market in China was a big break for the patriarch of the soon-to-be historic family:

Warren Delano first sailed for China at age 24 and, after a decade dealing drugs on the Pearl River, returned with a fortune that made him a highly eligible bachelor among New York’s elite. In letters home, Delano admitted that opium had an 'unhappy effect' on the cadaverous, zombielike addicts he encountered, but said of its sale that 'as a merchant I insist it has been … fair, honorable and legitimate, likening it to the importation of wine and spirits to America.

Delano made his fortune not once but twice from opium. He lost much of his money in the Panic of 1857, Braswell reports, and left behind a wife pregnant with their ninth child to sail back to the other side of the world to recoup his loss, in part by supplying medical-grade opium to the soldiers of the U.S. Army for the Union.

The Roosevelt family grew up in lavish wealth. And Braswell indicated that the family members had hoped to sweep their grandfather's shady dealings under the rug — and were probably quite successful, as evidenced by Cruz quoting their grandfather onstage. The quote has certainly made the rounds.

It's also not clear how much FDR knew about his grandfather's past, Meyer writes.

To be fair to Cruz, we should note that the Roosevelts weren't the only political elite family with ties to and gifts from the opium trade. Braswell writes that Harvard University has some of it and the founders of Yale's Skull and Bones society has some of it, as does the family tree whose lineage includes Secretary of State John F. Kerry.