AceShowbiz - Sean Penn often "butt heads" with his son Hopper in the past. According to his 29-year-old offspring - whose mother is Sean's ex-wife Robin Wright, the Oscar-winning actor-and-director used to be a "strict" father but he is "very lax" now because he has mellowed in his "older age."

"He was strict, and I was always getting into trouble. We butted heads for a long time. But it's very lax now. He's chilled out in his older age!" Hopper told People magazine.

Although father and son are close now, Hopper confessed to "rarely" reading his dad's text messages because they are so long. He said, "My dad is really into FaceTime and texting. But when he texts, they're like novels. He has to send them in increments. So I rarely read them!"

While growing up in Northern California meant the family were "pretty separate" from Hollywood life, Hopper admitted things changed when they moved to Los Angeles and he felt "awkward" at school because his classmates knew he had famous parents.

He said, "I knew that my dad was known and that my mom was known. And we'd go on movie sets. But when we moved back to [Los Angeles], things were said to me in school. It just made me feel awkward!"

Hopper, who starred with his dad in "Flag Day" last year, has more of an appreciation for the 62-year-old star's career now he's older. He said, " 'Milk' [is one of my favourites]. And then 'The Falcon and the Snowman'.

"But when he went to Haiti [after the catastrophic 2010 earthquake], I'd never seen that side of him. It was just immediate, and he was really smart with it. Emergency mode is his place. I feel like he's the calmest when chaos is going on. It's really great."