Colin Firth had concerns about kissing Nicholas Hoult in A Single Man because the younger actor is the same age as his son.

In the film, which is designer Tom Ford’s directorial debut, 49-year-old Firth plays a college professor upon whom Hoult’s character, a student, develops a crush. And Contact Music says Firth was worried about a scene in which the pair share a kiss because his son Will, 20, is just a few months younger than Hoult.

He reportedly said, “I did have conversations with Tom about the nature of the relationship. I have a son the same age as Nick so I was very concerned.

“I would have been uneasy had [Hoult] been uneasy but he seemed so calm about everything and displayed no self-consciousness whatsoever.

“But the nature of the scene wasn’t predatory on my part. If anything the young man is the stalker.”

Firth’s character, George Falconer, is a gay man in the 1960s, dealing with grief over the death of his longtime partner. The role won him the Best Actor Award at the 2010 BAFTAs.