The actress sat down to watch the 1999 sci-fi comedy with her twin boys ahead of appearing on cast member and pal Justin Long's podcast, and had to keep explaining her secret identity is not Sigourney Weaver.
"They were blown away by it but when Sigourney Weaver came on, one of them looks at me and goes, 'Mum, why didn't you tell us you were in this movie?' " Julie explains. "She's (Sigourney) got a wig and she's got a square jaw, and I was like, 'That is not me.' And they were like, 'Yeah, it's not, sure mom...'"
It's not the first time Julie and her kids have had identity troubles, though. At home there's a giant poster from a film, in which she did appear - 1996 Adam Sandler comedy "Happy Gilmore" - but this time her sons refuse to believe it's really her.
"In Ghana there are these movie clubs... and to advertise what they would be playing at the movie club that might, which was literally a TV in the back of some store, they would paint (posters) on these huge flour sacks (of) the most violent graphic scenes from the movie. And if there weren't any, they would make them."
"So I have a poster of Happy Gilmore..., where people are being killed and stabbed and there's blood, there's a monster and zombie - it's fantastic. I think it's a romantic golf comedy, a rom-com with golf. My fake (Modern Family) son Nolan Gould found it for me and gave it to me for my birthday."
But Julie looks so unlike herself in the odd depiction of her character, Virginia, her kids think it's someone else.
"On the movie poster I am portrayed roughly (and) they're like, 'That's not you!' I have, like, a Beyonce body, I have this itty bitty waist, and this giant a**... And they don't really think that's me. It's pretty good!"