Two shootings in El Paso, Texas, and Dayton, Ohio, claimed 29 lives over the weekend.

President Donald Trump on Monday blamed numerous factors including video games , mental illness, and racist hate for the shootings.

on Monday blamed numerous factors including video games It's become commonplace for politicians and media to blame violent video games for mass shootings , but there's evidence the two are not closely linked.

Psychology professor Patrick Markey co-wrote "Moral Combat: Why the War on Violent Video Games Is Wrong," and says that studies found about 20% of school shooters showed interest in violent video games, compared to the average high school student at about 70%.

Following is a transcript of the video.

Joe Lieberman: "This game encourages players to shoot this gun..."

Donald Trump: "I'm hearing more and more people say the level of violence on video games is really shaping young people's thoughts."

LT. COL. (RET) Dave Grossman: "There's a clear unequivocal link between violent video games and violent behavior"

Steve Kovach: Actually... no. That's fake news. We need to stop blaming violent video games for mass shootings. Violent video games are played all over the world but mass shootings are a uniquely American problem. So why have video games been getting the blame for the last 20 years?

Patrick Markey: "We go through this thing called a moral panic..."

Steve Kovach: This is Patrick Markey, a professor at Villanova. He literally wrote the book on violence and video games.

Patrick Markey: Typically the older generation is fearful of something a younger generation is adopting that they don't totally understand or they don't see value in."

Chris Christie: "All you're focusing on right now is gun control. What about the violence in our video games?"

Steve Kovach: That soundbite came shortly after the Sandy Hook shooting in 2013. And it's happening again now as students continue to fight for more gun control in the wake of the shooting in Parkland, Florida. President Trump even held a meeting with top video game industry executives on the issue. This is how he opened up the meeting. Gross, right?

But as unsettling as those images are, there's no link between violent games and real-world violence.

Patrick Markey: When we look at games like Grand Theft Auto and Call of Duty, the two games tend to be kind of lightning rods and are often blamed for school shootings. We find that when those games first come out there's actually sudden dips in homicides in the United States. We've also done other things on when are people actually playing violent video games, this is kind of across the board, any type of violent video game and what we find is when people are playing violent video games we also see dips in violent crime: aggravated assaults, homicides and so forth."

Steve Kovach: By the way, we fixed the problem of easy access to violent video games decades ago. Remember this guy? That's former Senator Joe Lieberman in 1993. He really hated violent games, and he pushed for game makers to do something about it.

The ESRB formed, and video games would receive age-appropriate ratings. The ESRB was born in 1994 to do just that. And guess what? It's worked out pretty well. According to the ESRB, about 80% of physical retailers and over 90% of online retailers comply with ratings.

They test the effectiveness by sending secret underage shoppers into stores to buy games rated Mature. That means it's nearly impossible for a child under 17 to walk into a store and buy the latest Call of Duty game, or any other Mature title. They can only play these games if their parents buy it for them.

But what about all those killers? Why do we keep hearing they play video games? That's because the demographics of shooters usually lines up with the demographics of video gamers: Young and male.

Patrick Markey: "In fact, again, what is found in both studies is about 20% of school shooters showed interest in violent video games. Whereas the average high school student is about 70%. So what we find is the actual reality is the reverse of what we tend to think, that the school shooters tend to play less violent video games than the average high school student."

Steve Kovach: Of course, there's going to be a strong chance a shooter also played a lot of games. So do millions of other young males. Now, look at Steven Paddock, the man who committed the largest mass shooting in the country's history. He was 64 years old — not even close to the demographic that plays games. As journalists and investigators hunted for Paddock's motivation, video games never came up.

It's the same with other horrible shootings in recent history. Many of these shooters don't match the gamer profile.

They don't fit the narrative of a young, disaffected youth addicted to violent video games, so it was never brought up as a motivation.

Just because young males tend to play video games and also tend to be the ones who commit mass shootings, doesn't mean the two are linked. It's like saying all shooters wear sneakers, therefore sneakers cause gun violence.

So the video game industry makes it difficult for young people to access violent games. There's no correlation between violence and video games.

But what's it like in other countries where these games are played? And what does gun violence look like there?

Japan is a great example. Video games are deeply ingrained in the culture, and they're often more violent or perverted than what you find in the US. Guess how many gun deaths there are in Japan? Fewer than 10 most years. In a country of about 127 million.

There's only one common factor in every mass shooting. It's not video games. It's not exposure to violent movies. It's easy access to a gun.

EDITOR'S NOTE: This video was originally published on April 4, 2018.