Milo Ventimiglia worked hard to fix his 'crooked mouth'

Milo Ventimiglia spent hours in the mirror as a child trying to correct his "crooked mouth".

The This Is Us actor was born with "dead nerves" in his lip, which caused one side of his mouth to droop, and he first noticed the issue while watching a video of himself speaking - and vowed to fix the problem.

"When I was young, I used to really talk out of the side of my face - it was that pronounced," he tells People magazine. "I saw an interview when I was a kid on the local news channel, and I remember saying to my mom, 'Mom, what's going on? That's how I talk? That's what I look like when I talk?'"

After the interview, the 39-year-old would sit in front of the mirror for hours and read a book until he started to see his mouth straighten out.

"Every time I'd catch myself getting this slanted, really pronounced mouth, I would figure out a way to straighten the word out - straighten my mouth out through the word and kind of correct that, so it wasn't as pronounced," he says. "Now, it only pops out if I'm running and yelling. If I'm running and yelling in a scene, I can't control it. It gets so crooked!"

The issue did make the beginning of his career difficult because casting directors would ask him to "stop doing that thing with your mouth, where your lip is going down" at auditions.

"I'd be like, 'Hey, I was born that way...' I mean, look, I can't get away from it now," he adds. "It's who I am, you know? I've got a crooked mouth."