These days, everyone knows NCT127‘s main vocalist, lead dancer, and visual as Jaehyun. However, that wasn’t always the case—in fact, he’s technically changed his name multiple times over the years.

When baby Jaehyun was born on February 14, 1997 in Gangnam, Seoul, his parents found themselves with a problem: they couldn’t agree on what to name him. Jaehyun’s mother loved the name Sunwoo, which would’ve led to him sharing his name with The Boyz‘s Sunwoo and ENHYPEN‘s Sunoo.

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The Boyz’s Sunwoo | Cre.ker Entertainment

Jaehyun’s father, on the other hand, wanted to name him Lin. In the end, the parents compromised by settling on a different name entirely…

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Baby Jaehyun | @NCTsmtown/Twitter

… They named him Jung Jaehyun. Confused yet? Yes, Jaehyun is Jaehyun’s birth name, but he later legally changed it. But why?

It all happened in middle school. Some idols, like TWICE‘s Jeongyeon, changed their names because they were bullied. Jaehyun, however, was incredibly popular in middle school according to one of his former classmates. In fact, he was described as the school’s legend. Plus, his parents were teachers there, so Jaehyun had nothing to worry about.

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Jaehyun as a child. | SM Entertainment

Instead, Jaehyun’s name was changed in middle school because of his grandmother. Alongside Hangul names, Koreans also have Hanja names. Hanja are Chinese-Korean characters that correspond to the name’s Korean syllables. However, Jaehyun didn’t have a Hanja name, because there’s no Hanja character for “hyun”.

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Jaehyun as a child. | SM Entertainment

In Jaehyun’s grandma’s view, that just wouldn’t do. So, his family decided to legally change his name to Jung Yoon Oh. The Hanja character his parents chose for Yoon means “intercalary” or “extra”, while the character for Oh can mean “five” or “military”.

So, why on earth did Jung Yoon Oh end up changing his name back to Jaehyun when he joined NCT? The answer most likely lies in TVXQ. Today, TVXQ’s lineup consists of two members: MAX Changmin, and U-KNOW Yunho.

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TVXQ | SM Entertainment

While Yunho and Yoon Oh aren’t exactly the same name, they sound pretty similar to the Korean ear. So, SM Entertainment likely asked Jaehyun to use a stage name to avoid any confusion. While he could’ve opted to create a completely new name for his idol career, it seems he decided to give his birth name center stage.

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| SM Entertainment

Surprisingly, those aren’t Jaehyun’s only names. He also took on the English name Jay when he lived in Connecticut, USA for five years, as his teacher couldn’t pronounce Jaehyun. Whatever the case, there’s no doubt this star would on track to become a household name whether he was known as Jaehyun, Yoon Oh, Jay, or something else entirely.

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| @NCTsmtown/Twitter