No i think the same,i don't know where is this about twin coming from
Okay so go to chapter 6 & 11, you will see a flashback of a blonde dude, that is Seo-in twin brother brother Jaewon who died (we have yet to find out how and why). On the kissing flashback we see on chapter 20, i am 100% sure that Jaewon died his hair back to black.
dyed**
Now that i think about it, he either is naturally blonde and dyed his hair black or maybe as a kid dyed his hair blonde to be distinguished from Seo-in. and then dyed his hair black.
im so confused in the comments about where the “seo-in twin theory” came from. i thought seo-in is adoptive, and he has one brother, which is the guy who looks like haeyool but with a mole. am i missing a hint???