For most of her life, Payton Lee never had a reason to question whether she and her four younger siblings shared the same parents, even if they didn’t exactly look alike. Then a running family joke about her being the odd one out led to a DNA test — and at 29, the punchline suddenly became her reality.

“The idea that I have a different dad than my four younger siblings had honestly never crossed my mind until a few months ago,” Payton tells PEOPLE. “I had always just thought none of us looked alike.”

The joking started after Payton returned to her hometown and her brother mentioned that her siblings had been talking about how little she resembled them, which she shared in a now-viral TikTok video. She laughed at first, but when she started comparing old baby photos, she noticed something she hadn’t before: her siblings and her nephew looked like one another, while she didn’t.

For the first time, a small part of her wondered whether the joke could hold some truth, though she says neither she nor the people around her seriously believed it. She likely would have left the question there, too, if her mother-in-law hadn’t surprised Payton and her youngest sister with DNA tests.

“I don’t think I ever would have bought or taken one if it was up to me,” she says. “One of the hardest parts of all of this has been that I never really made the choice to take that test, so I wasn’t emotionally prepared for what it could actually uncover.”

When the results arrived, Payton was out of town, so her siblings gathered at her sister’s house and they opened them together over FaceTime. Payton saw it first: the sister she had always believed was her full sister was listed as her half-sister.

She stared at the screen, confused enough that she initially wondered whether someone was pranking her. When she announced the result, her siblings responded, “We knew it,” a callback to their summer-long joke even as they were processing the same shock.

Then Payton kept looking, and the discovery got bigger. Directly below her sister’s name was another half-sister, someone Payton had never heard of, making it clear that the biological relatives appearing on her paternal side belonged to an entirely different family.

“That’s when it really hit me that the people on my father’s side were a completely different family,” she recalls. The result also meant something even harder to absorb: the man Payton had called Dad for 29 years was not her biological father.

Payton Lee and her sister.Payton Lee
Payton immediately called her husband, and once he returned home, they FaceTimed her dad to tell him what the test had uncovered. He didn’t believe it at first, but Payton says his response once they talked through the results quickly eased one of her biggest fears.

“He made it very clear that this doesn’t change anything and I’m still his daughter!” she says. For Payton, that reassurance carried decades of history behind it.