NEW YORK — O’Reilly Factor producer Jay Richards revealed today the unlikely cause behind Bill O’Reilly’s explosive on-screen rage: the boisterous host is not actually the hair-trigger conservative blow-hard he seems to be, but for the entirety of the show’s run, the caps-lock on the studio teleprompter has been left on.

“This explains so much,” said journalism legend Bill Moyers in a PBS blog post. “O’Reilly isn’t inexplicably furious over a rapper visiting the White House or people saying ‘happy holidays.’ That would be psychotic. He’s just giving an accurate reading of the lines as he sees them.”

According to an internal investigation, the caps lock was used during The Factor’s first episode to cover a NASA shuttle launch. With the deadline closing in, then-scriptwriter Dale Evans hastily wrote the rest of the episode in aggressive all-caps.

“At first we tried to scale back Bill’s volume and intensity,” Richards told reporters. “We just couldn’t figure out why he was screaming over the smallest perceived slights and most mundane news.”

But the show’s instant ratings success lead Fox executives to stop questioning the formula.

“The delivery is way over the top,” confided Fox News President Roger Ailes. “But when you’re doing a thirty-share and bringing in those lucrative Life Alert ad dollars, you’re doing something right. So we went with it.”

O’Reilly’s apparent rage inspired a formula that lead Fox News to dominate the cable news world. But now that the cause of O’Reilly’s charisma has been discovered, executives say they have no plans to change the show’s tone.

“If anything we’ll start hammering on the bold and underlining,” says Richards. “But we will have to stop scripting ‘Fox and Friends’ in comic sans. They really aren’t as stupid as they sound.”