Home Alone fans only just realising Macaulay Culkin's younger brother Kieran was also in film

We're just a few weeks away from the big day now and, no doubt, we've all been movie marathoning all our favourite festive flicks to really get into the spirit.

After you've cried your eyes out to the likes of Love Actually, laughed your socks off to The Grinch and cosied up to The Holiday - it's only a matter of time before you go full-nostalgia and whack on the Home Alone movies.

The hit family comedy first warmed our hearts over 30 years ago back in 1990 starring a baby-faced Macaulay Culkin, Joe Pesci, Daniel Stern, John Heard and Catherine O'Hara.

As we all know by now, the first film's plot centres around eight-year-old Kevin McCallister (Culkin) who is accidentally left behind when his family leaves for France. At first, he's happy to be in charge; but when thieves try to break into his home, he puts up a fight like no other.

After the success of the first film, five movies in the franchised followed - however, it was only Home Alone 2: Lost in New York which starred Culkin again.

Macaulay Culkin as Kevin McCallister in Home Alone (20th Century Studios)

While the flicks have a very dedicated, die-hard fanbase who can practically recite entire scenes off by heart, it's clear there's still some stuff they don't know about the films, despite watching it probably a million times. Some Home Alone fans are only just realising Culkin's younger brother, Kieran, was also in the film.

The next time you whack the holiday classic on, look out for a little Kieran in his first on-screen role.

And, surprisingly, Kieran didn't star as one of Kevin’s many siblings but was actually his younger cousin, Fuller - the kid who wets himself.

Kieran Culkin starred as Kevin's cousin, Fuller (20th Century Studios)

At the start of the film, when the family are all eating pizzas during a very chaotic dinner, Fuller - donning a pair of glasses and very 90s dungarees - is told to 'go easy on the Pepsi' given his rep as a bed wetter.

While it may have seemed like just a funny joke at the time, this character detail pretty much set up the plot for the entire film as Kevin was meant to share a bed with Fuller the night before the family all jetted off to the land of baguettes.

However, after getting told off, Kevin's mum sends him to bed.

Voicing his unhappiness with potentially sleeping next to a bed wetter, Kevin's mum - played by Schitt's Creek icon Catherine O'Hara - then instructs him to sleep in the attic.

And we all know what happened next...