HBO’s sex-and-swords drama “Game of Thrones” is one of the top-rated shows for viewers in their 20s. (Helen Sloan )

The TV industry should study whether there’s a link between onscreen violence and mass killings such as those last month at Connecticut’s Sandy Hook Elementary School, FX President John Landgraf told TV critics Wednesday.

But, Landgraf said, the incidence of homicide by gun is 90 times higher in the U.S. than in the U.K., and “we consume the same media — same movies, same television show, same video games.”

“The major difference between England and the United States is access to, and availability of, guns,” he said at Winter TV Press Tour 2013.

“I’m someone who believes very strongly in both the First Amendment and the Second Amendment, so I believe that we have the right to free speech in this country, and I believe that we have the right to have guns for protection,” said Landgraf, who is much loved by TV critics because he is the only cable TV exec who consistently appears at the tour to take questions on the record.

“But last time I checked, I think a shotgun or a handgun that has a six-round clip are . . . perfectly adequate weapons for self-defense in the home. I think it was yesterday, it came out that the crazy man . . . who shot up the movie theater in Aurora got off — it was either 27 shots in 30 seconds or 30 shots in 27 seconds. . . . You simply can’t create that kind of mayhem if you have to reload.”

Asked about the pile-on of violent TV shows, Landgraf said: “We’re animals — our greatest fear is death, and if you want to rivet people . . . you’re going to tend to hover around questions of life and death, because that’s the thing that rivets our attention.”

He noted that the top-rated dramas/miniseries on cable among young viewers (who are coveted by advertisers) are: AMC’s zombie drama “The Walking Dead,” History’s “Hatfields & McCoys,” HBO’s vampire drama “True Blood,” Fox’s biker-gang drama “Sons of Anarchy,” FX’s horror anthology “American Horror Story” and HBO’s sex-and-swords drama “Game of Thrones.”

“The top six are all in some way about violence,” he said. “Let’s not kid ourselves; that will always be very compelling for people to watch.

He noted that such shows as “The Walking Dead” and “Sons of Anarchy” are tailored to appeal to viewers in their 20s.

“You think it’s just that younger people’s fears tend to go more towards zombies?” one critic asked.

“I do,” Landgraf said. “I’m 50. I worry about cancer.”

Rock on Glocks

Chris Rock — the exec producer of FX’s late-night show “Totally Biased With W. Kamau Bell” — famously suggested years ago in his stand-up routine that guns should be made available to anyone, but that bullets should cost $5,000 a pop.

On Wednesday, Rock updated that line: He suggested that instead, only those who have mortgages should be allowed to own guns.

“The gun lobby . . . says people need to be able to protect their property, but every mass shooting is done by guys who live with their mother.

“So I believe you should need to have a mortgage to buy a gun. A mortgage is a real background check.”

Kimmel’s new night

On Jimmy Kimmel’s first night in his new time slot, Jay Leno won the late-night ratings war.

On Tuesday, an average of about 3.1 million people checked out Kimmel’s first broadcast at 11:35 p.m. on ABC — his second most-watched episode ever.

But Jay clocked 3.3 million — and without any heavy lifting. His guests were Josh Gad, star of the new NBC comedy “1600 Penn,” and Emma Stone. (Jay’s starting at 11:34 p.m. these days, a minute early.)

In his first night competing directly against Leno and CBS’s David Letterman for his full broadcast, Kimmel did edge out his idol Dave, who snagged 2.8 million viewers.

For Kimmel, the rating was about 60 percent better than his season average of just less than 2 million in his old midnight start time this season.

Leno also trounced Kimmel among the 18- to 49-year-old viewers. Leno clocked 1.1 million of them to Kimmel’s 890,000; Letterman trailed with 683,000.

Meanwhile, “Nightline” — which got bumped from the 11:35 start time to make way for Kimmel — beat NBC’s Jimmy Fallon and CBS’s Craig Ferguson among overall viewers. It’s unclear how many minutes of “Nightline” were rated by Nielsen. When it used to start at 11:35, Nielsen only rated 17 minutes of the news program.

That practice came back to haunt ABC on Wednesday morning, what with Kimmel’s first night numbers being compared with “Nightline’s” season average of 3.9 million.

“Thank you for joining us here. A new studio, new time slot. I appreciate it. The deal is this: we used to be on at midnight. Now we’re on at 11:35. Now 25 minutes closer to my lifelong dream of co-hosting ‘The View,’ ” Kimmel said while opening a very adequate, nothing-special first show in the new time slot.

“We’ve been waiting for this day for a long time. And I want to thank our network, ABC, for this vote of confidence,” he said. “It was a big decision. It’s a risky decision. . . . I want them to know that I understand what’s at stake here, and I do not take this responsibility lightly, especially now with the Kanye West-Kim Kardashian baby on the way. This is the time that I shine bright like a diamond.”

Kimmel added: “For those of you who tuned in expecting to see ‘Nightline’ right now, this is not it. ‘Nightline’ is on after us now, and I hope you stay up to watch it, because it’s a great show. But just because this isn’t ‘Nightline,’ that doesn’t mean we’re not going to talk about important stuff. For instance, did you know Honey Boo Boo’s mother is afraid of mayonnaise?”

And the show cut to one of many taped bits — used to gobble up opening-monologue time — before he introduced his first guest at the new hour: Jennifer Aniston. She destroyed Kimmel’s faux desk with a sledgehammer and pretended that she thought it was his last night in his old time slot. Then she gave him a haircut.

Been done before.

Kimmel would have been better served having a comedian join him on stage his first night. There’s a reason Letterman asked Bill Murray to be his very first guest when he launched both his NBC and his CBS late-night shows.

Likewise, Leno asked Billy Crystal to help him through his first night as permanent host of “Tonight.”