Rebecca Tyrrel: 'Having a Gene Kelly wannabe bursting into the bedroom at 4am must have been a trial for Jim Carrey’s mother'

Who knew that when Jim Carrey was a child he wore tap shoes to bed in case his mother and father needed cheering up in the middle of the night?

For those of us who were not his parents, this is an endearing fact about the first actor to break the $20m-per-film barrier. His inherent likeability somehow transcends the desperation to please, which is not, for instance, the case with Robin Williams, his spiritual father in the art of permanently trapping the precocious four-year-old exhibitionist in the body of a man.

Carrey says his mother, Kathleen, was depressed throughout his early years. While this may not have been due solely to the misery of raising a hyperactive, rubber-faced gurner, it can hardly have helped. Having a Gene Kelly wannabe bursting into the bedroom at 4am, half an hour after she'd popped a Mogadon, must have been a trial on the poor woman's nerves. Nor can she can have been comforted by such fall-back methods of spirit-raising as impersonating a praying mantis, although that will at least have been quiet, or comedically bouncing off the walls or down the stairs, which will not.

Jim, who has observed that "if there had been Ritalin when I was a kid, I wouldn't be here now", grew up only in a manner of speaking. He married young (at not yet 50, he is already a grandfather). He then married again, the second wedlock enduring for a marathon 10 months. Judging by the number and speed of his relationships (he's currently attempting to woo 22-year-old actress Emma Stone via video blog) it clearly remains difficult to live with him.

"I tend to stay up late, not because I'm partying," so he says, "but because it's the only time of day when I'm alone and I don't have to be performing."

For all that, his devotion to fighting other people's blues survives in the hours of daylight. "You are either in a loving place, or you are in an unloving place. If you are with me right now, you cannot be unhappy. It's not possible, just try."

This is a man whose daily greeting, on arriving on a film set, is "Hey humans. How are you doing? Let's have fun. Let's play in the sandbox." His parents got off lightly with the tap shoes.