Because in one episode of Tucu's home there was a photo of a man holding twins standing next to a little boy about 5 years old the little boy waist wearing a Golden buckle belt;

And in Tu Ku's stills our careful netizens also found the exact same belt on the waist;

While there is no name list, but we can not help but deduce that they can be photographed together as a child even if it is not a relative, and their fathers are also very close friends.