Gong Yoo and Shin Won Ho are not brothers but 'Fraternal Twins.'

On the 14th episode of 'Big' that aired on July 17th, it was revealed that Kyung Joon(Shin Won Ho) and Yoon Jae(Gong Yoo) are actually fraternal twins not brothers.

Last episode Kyung Joon finds out that he and Yoon Jae are brothers leaving him in a state of shock.

Kyung Joon's soul still inside Yoon Jae's body, Kyung Joon stated "If people find out that I'm in precious Yoon Jae's body they are going to get shocked. If they find out who I am their bloods are going to dry out."

While having a meal with his parents, Yoon Jae's mom Hye Jung(Kim Suh Ra) stated "You know I could've have that child instead and raised him instead" and revealed that because her body was weak Yoon Jae was an externally conceived child.

Then his father In Wook(Jo Young Jin) went onto state "You two may not be 12 years apart but may be fraternal twins."

Hye Jung right after stated "If Kyung Joon was picked first then I would've had him and raised him not you."

It was revealed that the two were not just brothers but the two could've had different fates.

But Kyung Joon in the end replied to the parents comment with anger, "You two decided the fates then. Before it was Kyung Joon waiting. This time it's Suh Yoon Jae. Have fun waiting."