The runaway rumour Kourtney Kardashian couldn't ignore.

There's always a million and one rumours about the Kardashians. From the ridiculous (remember when people thought Kris Jenner was actually behind Taylor Swift and Kanye's feud?) to the hilarious (the conspiracy theory that Scott Disick had dated… well, basically the entire family), the internet loves nothing more than a wild theory about America's most famous family.

But this time, the internet took it a step too far, and Kourtney Kardashian isn't having it.

Recently, rumours began circulating on social media that Kourtney's 15-year-old son, Mason Disick, had secretly fathered a child. The speculation spread quickly after Instagram accounts claiming to be "secret profiles" belonging to the teenager shared posts suggesting he had become a parent.

Watch Kourtney Kardashian arguing with sister Kim on their show. Article continues after video.

The rumours became so widespread that Kourtney did something she rarely does — addressed gossip about her family directly.

"I rarely address rumours or conspiracies regarding myself or my family, but this is about my child," Kourtney wrote in a statement shared to her Instagram stories.

"It feels wrong to let anyone think for a second that these lies are remotely true. They are not."

Kourtney said the record straight. Image: Instagram/kourtneykardash.

She continued with a clear denial: "Mason does not have a child."

The Poosh founder and reality star also clarified that the social media accounts claiming to be her son were "fake" and asked for respect for her child's privacy.

"My son really values his privacy, and I am asking all media to please be respectful: he is a kid with feelings and a beautiful life ahead of him. Please stop spreading false narratives and spinning lies," she wrote.

Kourtney and husband Travis' growing family. Image: Instagram/kourtneykardash.

And that's the crux of why this particular rumour crossed a line — Mason is a minor.

Given Mason started off appearing on reality TV with his very famous family, many people forget that, at just 15 years old, he is a child.

Kourtney, who shares Mason with her ex Scott Disick, has been increasingly protective of her eldest son's privacy in recent years. Mason has largely stayed out of the public eye and doesn't appear regularly on The Kardashians or on his mother's social media.

Regardless of his famous family name, starting a rumour like this one about a literal child feels very icky. It crossed a line.

Feature Image: Getty / Instagram/masondisick.