Kenneth Starr’s investigation of President and Mrs. Clinton began with a look into the first couple’s real estate dealings.

Then it morphed into something quite different. A blue dress emerged with some DNA on it, linking it to a relationship between the president and a young White House intern.

Starr, a special prosecutor, summoned the president before a grand jury and asked him about the relationship. President Clinton didn’t tell the truth.

Boom! We had an impeachment!

Two decades later, special counsel Robert Mueller’s probe — which began as an investigation into possible collusion with Russians who hacked into our 2016 presidential election — might be heading down a similar path.

Donald Trump allegedly had an affair with a porn queen in 2006. He has denied it. The president’s personal lawyer, Michel Cohen, has acknowledged writing a $130,000 check to keep the porn queen quiet about an affair — again, that the president says didn’t happen.

So, here comes the latest Big Question: Where did the money come from to pay the porn actress? Cohen says he paid it out of his personal account.

Meanwhile, you and I know that Mueller’s antennae have been alerted. The special counsel/former FBI director is a meticulous lawyer. There just be be some dots connect between the Russian probe and this seedy, crappy, tawdry affair.

Looking back on the Starr investigation, I am perplexed at how the special prosecutor connected the dots between real estate and a tawdry relationship between the president and a much younger woman. But he did.

Might history be repeating itself?