Responses
You know his dad is/was the goat
I don't think dad has been shown yet, but he's almost certainly the 4th/5th member of the group and looks identical is what I'd guess-
He hasn't been shown yet, the is/was is me wondering if he's alive or not
Jigu and his two older brothers look like triplets, but IIRC they're all like 1 or 2 years apart - they're COMPLETELY IDENTICAL except for their hairstyles and personalities, and their mom is a smaller lady. The nephew looks like the boys, but he's like 5 years old.
The older brothers are a lot more extroverted than him irl, and the oldest seems to be the most "obedient" and has shorter hair than either son we've seen so far in the translated versions.