In the manhwa Chase should be early 20, Josh is 5 years older.
I guess that Pete is 2-3 years old.
The author didn't give any ages, but age differences. Chase oldest brother is ~
6 -7 years older than him ( who was born when their parents were ~29 years old), the twins ( should be the same age as Keith Pittman) 3 - 4 years older than him.
That story plays in the US, so even 18 would have been ok. But since it's written in korean, so the main audience are koreans, the author would at least avoid giving the ages.
I think that Grayson and Dane are in their early 30th in Desire me if you can, which would make Chase around 28. It then depends on how old the children of Josh+ Chase and the Pittmans are to estimate how much time has passed between KMIYC and DMIYC, but their ages aren't mentioned either.-_-
It would be so much easier it the author would mention Nathaniel's age in his currently running webnovel, but I think only this hights was mentioned so far.
And it also doesn't help that Koi doesn't really look old, since dominants age slower.

guys can anyone tell me what’s their age?