As the old expression goes, “it takes one to know one.”

President Biden’s pick to lead his Department of Homeland Security’s Big Brother-like Disinformation Governance Board has her own history of posting disinformation online.

Nina Jankowicz, who was a disinformation fellow at the Wilson Center, has repeatedly cast doubt on The Post’s reporting about Hunter Biden’s laptop.

During a series of live tweets during the presidential debate between Biden and Donald Trump in October 2020, Jankowicz had referenced the laptop.

“Back on the ‘laptop from hell,’ apparently—Biden notes 50 former natsec officials and 5 former CIA heads that believe the laptop is a Russian influence op,” Jankowicz tweeted.

“Trump says ‘Russia, Russia, Russia,’” she added.

Her tweet resurfaced immediately after she revealed she’d been named executive director of the new disinformation bureau on Wednesday — as conservatives slammed her as a “leftist radical” and expressed doubt in her ability to spot misinformation.

Jankowicz tried to brush off the controversy surrounding her old laptop tweet, saying: “For those who believe this tweet is a key to all my views, it is simply a direct quote from both candidates during the final presidential debate. If you look at my timeline, you will see I was livetweeting that evening.”

But the Russian misinformation expert had told the Associated Press just a week earlier that there was doubt the laptop even belonged to Hunter and there were multiple red flags that emails uncovered from the device were legit.

“We should view it as a Trump campaign product,” Jankowicz said at the time.

Jankowicz had also tweeted a link to a news article in October 2020 that she said cast “yet more doubt on the provenance of the NY Post’s Hunter Biden story.”

“Not to mention that the emails don’t need to be altered to be part of an influence campaign. Voters deserve that context, not a [fairy] tale about a laptop repair shop,” she added in another tweet.

Wisconsin Sen. Ron Johnson slammed Jankowicz on Wednesday as a “beacon of misinformation” over her dismissal of the laptop – and accused her of “furthering the false media narrative” with her series of tweets.

Jankowicz, who has researched Russian disinformation tactics and online harassment, also previously praised Christopher Steele — the author of the since-discredited Trump-bashing dossier.

In August 2020, Jankowicz tweeted about the former British spy’s appearance on the Infotagion podcast, writing: “Listened to this last night – Chris Steele (yes THAT Chris Steele) provides some great historical context about the evolution of disinfo. Worth a listen.”

Steele’s fake dossier, which sparked the probe into whether former President Donald Trump or his campaign colluded with Russians during the 2016 election, was eventually debunked by special counsel Robert Mueller’s investigation.

More recently, Jankowicz flagged concerns about the potential for Elon Musk to takeover Twitter.

“I shudder to think about if free speech absolutists were taking over more platforms, what that would look like for the marginalized communities,” she said in an interview with NPR ahead of Musk’s takeover deal emerging.

Since then, the billionaire Tesla CEO has vowed to make it a free speech haven.

Missouri Republican Sen. Josh Hawley seized on Jankowicz’s tweet about free speech, tweeting: “The Biden Administration’s new anti-speech czar is apparently no fan of the ⁦@elonmusk⁩ Twitter acquisition. This is the person Joe Biden just put in charge of policing Americans’ speech. Using the power of the government.”

Jankowicz and the DHS didn’t immediately respond to The Post’s request for comment.

White House press secretary Jen Psaki had no comment when asked about Jankowicz’s ability to head the disinformation board during Thursday’s media briefing.

“I don’t have any comment on the laptop … And I don’t know who this individual is, so I have no comment on that specifically,” Psaki told reporters.