Los Angeles, California - Baby, baby, baby, oh! Kourtney Kardashian's 10-year-old son Reign Disick just reacted to the longstanding fan speculation that his biological dad is secretly Justin Bieber and not Scott Disick.

Scooter Jackson – the boyfriend of Reign's step-sister Alabama Barker – recently brought the kiddo in on an Instagram Live when a follower commented about the Bieber rumor.

"Bro, I swear," the seemingly flustered Reign said.

"Justin Bieber's not my dad," he added, noting that "Scotty" was his real father.

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There were widespread rumors of a romance between Kourt (45) and Justin (31) back in 2015, soon after the reality star broke up with Scott.

"I think Justin Bieber was 16 when I got born," he added, although the Peaches singer had actually been 20 at the time.

"Yeah, I don't think my mom would do that."

Over the years, fans have speculated heavily about the "true" paternity of Reign, drawing fuel from the striking resemblance between the two and the child's blonder-looking hair as compared to his siblings' darker locks.

"Kourtney doesn't give any heed to the reports that Justin is Reign's father," an inside source told Us Weekly on Tuesday.

"She thinks it's ridiculous and laughs that people online would even believe that."

Kourtney has always maintained that Reign's father is Scott Disick, who also shares daughter Penelope (12) and son Mason (15) with the Poosh founder.

The Kardashians star recently gave birth to 16-month-old Rocky with her husband, Travis Barker.