(CNN) President Trump's world-famous bone spurs, which kept him out of the military draft during the Vietnam War, are back in the news. The New York Times tracked down daughters of podiatrist Larry Braunstein, who diagnosed Trump in 1968, and reports that the President's father, Fred, may have arranged for the medical report, providing attentive service as the doctor's landlord in return. Notably, Braunstein's daughters, both Democrats, are not supporters of President Trump.

"What he got was access to Fred Trump," Elysa Braunstein told Steven Eder of the Times . "If there was anything wrong in the building, my dad would call and Trump would take care of it immediately. That was the small favor that he got."

A former colleague said Dr. Braunstein "spoke very highly of the Trumps, and they were very open to negotiating with him and letting him stay in the space at a rent he was comfortable with."

There is, however, no documentation to back up these accounts. (The Braunstein daughters did not return my calls seeking comment.)

Then there is the question of how a bone spur diagnosis by a podiatrist might have been enough to convince military doctors that Trump was medically unfit to serve.

The bone spur story is something I discussed with Trump when I interviewed him for my biography of him, "Never Enough: Donald Trump and the Pursuit of Success," published in 2015.

As with so many things we explored in many hours of interviews, this one required a painstaking dissection of Trump's record in order to sort out. In the past, he had noted student deferments and a high number in the draft lottery, which was based on the birthdays of eligible men, to explain why he never served in the military. He even talked about watching the lottery on TV while he was at the University of Pennsylvania to see how he fared.

Having learned to check and double-check everything Donald Trump claimed, I had done the research to determine that the lottery had nothing to do with his Vietnam draft status. According to his Selective Service record, he was granted a medical deferment a year before his lottery number was assigned in December 1969 (though his precise diagnosis was not included).

Few issues mattered more to Americans of the Vietnam era than who served and who didn't. Theoretically, every male of a certain age was subject to being drafted. However, there were exemptions granted to college students and those who could obtain the right kind of letter from a doctor -- and those exemptions contributed to a great divide between those who fought and those who stayed home. Add the anti-war sentiments that grew into campus protests and the death toll that mounted among those who shipped out, and the division became even more bitter.

In my interview with Trump, I broached the subject with care, but insisted on getting to the bottom of things:

Interviewer: I want to get this resolved, and I want you to help me figure it out and deal with it.

Donald Trump: Go ahead.

Interviewer: The draft thing.

Trump: OK.

Interviewer: Your (lottery) number was very high.

Trump: Right.

Interviewer: But that was 18 months after you became eligible (for deferment).

Trump: I don't know. I'm going to have to get the facts because they have a whole thing written down. I will get you facts, but it's very, very easy. Number one, the good news is I had a very, very high draft number.

Interviewer: Let me finish, because I really want ...

Trump: Because I have it written down. I'd rather give you exact dates and details. I have it written downstairs.

Interviewer: I don't do the gotcha thing. I come to you.

Trump: Right, I understand that.

Interviewer: So you did have a medical deferment.

Trump: Feet.

Interviewer: What was it for?

Trump: The medical deferment is feet.

Interviewer: So what was going on with your feet?

Trump: I have spurs on the back of my feet, which at the time, prevented me from walking long distances.

Interviewer: So you couldn't march?

Trump: It would have been very difficult to march long distances. Very healthy, but in the back, in fact it is here. You can see it on both feet. I have spurs.

As he explained his condition, the man who would become president took off his shoes and pointed at his right heel. He asked me to take a look for bumps, which I didn't actually see, but I gave him the benefit of the doubt because that's what a polite person does. He blamed misunderstanding about the issue on his off-the-cuff style, which left people with the impression that he was the lucky beneficiary of the lottery picks and not someone who had sought to be excused for a minor medical problem.

In our interview, I thought matters were settled and that he had acknowledged the truth, but very little stays settled where Trump is concerned. Just weeks before my book was published, then-candidate Trump revisited the topic and reverted to his old story, "I had a minor medical deferment for feet, for a bone spur of the foot, which was minor," he said. "I was fortunate, in a sense, because I was not a believer in the Vietnam War. ... But I was entered into the draft and I got a very, very high draft number."

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Why did Trump do this? I don't think it's because his story is better or less complicated than the actual facts. I think it's because going with the facts would require him to back down from his original tale about how he was saved by the lottery number. And, as everyone knows, the President never backs down.

For the record, I believe Dr. Braunstein's daughters, who think the bone spur diagnosis was made as a favor for the powerful Fred Trump that paid dividends for many years. Favors, like loyalty, loom large in the Trump family's scheme of things. ( Recently, he explained that he hired his one-time lawyer Michael Cohen, who has turned against him in court, because he had done him a significant favor.)

And there's also the glaring fact that when Trump showed me his feet, as if expecting me to see some type of visible abnormality, they looked pretty standard.