Francis Ford Coppola's actress/director granddaughter Gia made her adaptation of James Franco's book Palo Alto a family affair by casting Val Kilmer and his son Jack.

The filmmaker has known Kilmer's kid all her life and attended the same elementary school as Jack, and while she was working behind the scenes on her grandfather's 2011 movie Twixt, she got to know his dad too and thought it would be great to offer father and son roles in her directorial debut.

She tells WENN, "I've known Jack since he was four years old. We went to the same elementary school and in sixth grade I had to mentor his class, so he's been in and out of my life since he was a little kid.

"In that time of working on Twixt I got to be really close to Val, and Jack would come to set. It was really important when I cast Jack. I wanted it to be his movie and not have Val take away from that in any way, but he's a great actor and I wanted to work with him. So I gave him a fun little role of Emma (Roberts)' stepfather."

And the young Kilmer was thrilled to work with his dad in his acting debut: "He's always supported me, whatever I'm into and, as an actor, he told me to be as honest as possible and to follow my instincts."