Liam Hemsworth said his childhood in Australia with older brothers Chris and Luke was "like the Hunger Games" as he relived a dangerous incident with a knife.
The Independence Day: Resurgence star, 26, found worldwide fame as rebellion solider Gale Hawthorne in the violent franchise, a role for which he apparently needed no practice.
Speaking to Graham Norton, he said: "Our childhood rivalry was a bit vicious - a bit like the Hunger Games actually."
Admitting he didn't like to mess with eldest brother Luke, he clashed with 32-year-old Chris because "we were very like-minded, very stubborn and would often get into arguments".
He continued: "Because I was so much younger and smaller I had to use weapons to fight.
"So one day when I was about five we had a fight in the kitchen about using the toaster, or something, and I picked up a kitchen knife and threw it at his head and the handle hit him in the forehead."
He joked: "I could have hit him with the other end if I'd wanted to - it was just a warning shot!"
The news is probably a relief to Thor star Chris, whose face helped earn him 2014´s coveted Sexiest Man Alive title.
There's no chance he'll star alongside his siblings though if he can help it.
He said: "It would be really tough. I did a TV show about 10 years ago with Luke and he came in for a day's work. All the cameras were on me and Luke was trying to distract me all the time - brotherly love!"
Liam may look tough, but he also admitted that his new role is the alien-fighting Independence Day sequel next to Jeff Goldblum had left him with bad dreams.
He said: "My work really affects my home life and I had terrible nightmares that Jeff and I were being attacked by aliens.
"I actually had dreams that we were running away from aliens. We weren't fighting them, just running away!"
The Graham Norton Show airs on Friday on BBC One at 10.35pm.