For Sean, sci-fi is in the genes.
There was a gargoyle over his bed and at night, the creature's eyes would glow with evil.
Sean Pertwee, you can take it for granted, had an exceptional childhood.
Now the 46-year-old son of the late, legendary Jon Pertwee is making a sci-fi foray of his own in Ultramarines: A Warhammer 40,000 Movie, based on the tabletop game.
A special edition DVD cut of the film is just out, with Sean voicing the CGI character of Brother Proteus, who must lead his unit when its commanding officers are killed.
Bizarre Making the film was, he says, an eye-opening experience.
"I turned up at the readthrough and couldn't believe my eyes," he says. "I walked through the door and there was Terence Stamp and John Hurt.
"To be honest, I was terrified!
We were shooting at Abbey Road as well, which in itself was amazing.
It was a bizarre but great experience, especially meeting and working with those guys."
Although he's never played the game, Sean says he soon got into the Warhammer zone. I was mindful that the movie was made specifically for the fans so we had to get it right.
"A lot of it went over my head but all we can hope to have done is our job. It's up to the fans whether they like it.
"They gave me a starter pack and now my son is keen on it," he adds.
"Being a typical eight-year-old, it's not about him painting the pieces, it's about getting me, his dad, to do it."
Of his own dad's Doctor Who fame, Sean recalls: "As a kid I used to spend every Saturday hanging out with the special effects guys. So they gave me things like Auton hands, which have little guns inside them and stuff. "I had a weird gargoyle in my bedroom from an episode called The Daemons. You could plug it in and his eyes would light up.
"I had a giant spider as well, and props from an episode called The Green Death. Dad had Bessie, the old car the Doctor used to own. I drove around in that many, many times. It was very cool!
"Now my own son absolutely loves Doctor Who. He's a huge fan.
"And he gets a lot of respect at school because his grandad really was Doctor Who!" PC
GAME PLAY: Sean Pertwee provides the voice of CGI character of Brother Proteus in Ultramarines: A Warhammer 40,000 Movie