Fox, who has a 1-year-old son with Billie Piper, explained that he didn't connect with his baby at first.
"I definitely went through really odd feelings, really animal ones such as, 'Do I even want this baby?'" he told the Daily Mail. "I was like that for about two weeks after he was born. At one point I wanted to go and set fire to all my possessions. Very odd."
Fox added that he now has a great relationship with his son as one day everything "clicked".
He said: "I think some of it is that men can have babies whenever they want, so until they actually connect with this baby, then it's tough, but then it suddenly happens, like that.
"Suddenly I looked at him and thought, 'You're called Winston' - I'd called him 'it' for ages, as in, 'It's doing that' - and then it just clicked. And that's when you become - it's awful, isn't it? When clichés are true - but that's when you go, 'I'm not going to ever let anything bad happen to you, ever'. And now he's just a joy."