Even the most prepared interviews can be undone when a child makes an unexpected appearance. (Thomas Johnson/The Washington Post)

The professor at the center of the BBC interview that was seen around the world (no exaggeration) has finally spoken out about what caused his two adorable children to gate-crash his Skype appearance.

Robert E. Kelly and his wife, Kim Jung-A, told the Wall Street Journal that their family tried to lay low after being overwhelmed with phone calls, messages and interview requests following Kelly's now-infamous BBC spot.

But now, the newspaper said, the family was giving “their first interview since their children interrupted a live BBC segment on Korean affairs.”

And it answered several pressing questions people had about the viral video clip:

Had Kelly been wearing pants?

Yes, but they were jeans.

Why hadn't he locked the door to his office?

It was something he usually does, but he forgot that day.

Did their daughter, the one in the yellow sweater from the video, always march into a room with so much swagger?

“She was in a hippity-hoppity mood that day because of the school party,” Kelly told the Journal, in another apparent video interview.

Kelly also returned Tuesday to the BBC, to chat with presenter James Menendez about their original exchange — and its aftermath.

Unlikely internet celebrity Professor Robert Kelley recounts the moment his children interrupted a live BBC interview, which has now gone viral. (Reuters)

Kelly said assumptions that Kim was a nanny, and not the children's mother, made them “pretty uncomfortable.” But they also said they appreciated why most people found the video so funny.

“We watched it multiple times, too, and our families have watched it as well. Everybody we know seems to think it's pretty hysterical,” Kelly told Menendez. “It was sort of catching a regular family off-guard and stuff. It's funny.”

“We laughed a lot,” his wife added.

And, in an incredible confirmation of what many people had suspected, the Journal reported that Kim had not realized that the children had wandered into their father's home office — until she saw them on the TV screen.

“As the interview began, the couple’s 4-year-old daughter Marion jumped up and down at the sight of her father on the screen. Perhaps recognizing his location, a room at the end of the hallway, she wandered off to find him,” the Journal reported.

The couple’s 8-month-old son, James, followed behind his sister in his baby-walker, as he often does. Ms. Kim continued to concentrate on the screen, filming her husband.

Then, there she was: Marion was in the same room as her father in a bright yellow sweater.

It was, Kelly told the newspaper, “a comedy of errors.”

Kelly is an international relations expert and political science professor at Pusan National University in South Korea. A well-known analyst on Korean matters, he has provided expert opinion for a number of media outlets, including The Washington Post.

On Friday, he had been invited to speak to BBC World News about the impeachment of South Korean President Park Geun-hye.

He told the Journal that he has been making television appearances for six years, but this was the first time his children interrupted him.

Kelly said he and Kim were “mortified” at first but were not angry and didn’t scold their children.

He did worry he wouldn’t be asked to return on television — but some of his fears subsided after receiving so many positive responses as the clip went viral. (Comedian Trevor Noah called it "the greatest moment in the history of television, ever.")

“I made this minor mistake that turned my family into YouTube stars,” Kelly said. “It’s pretty ridiculous.”

At this point, the video has been dissected with a fervor normally reserved for sports replays.

There was the daughter’s jubilant entrance.

The mom’s slide into the room.

The epic arm-reach for the door.

“I mean, it was terribly cute,” Kelly told the Journal. “I saw the video like everybody else. My wife did a great job cleaning up a really unanticipated situation as best she possibly could. . . .

“It was funny. If you watch the tape I was sort of struggling to keep my own laughs down. They’re little kids and that’s how things are.”

Lindsey Bever contributed to this report.

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