omg! yas! never thought about it that way but that makes sense! really hope that theory comes true!
Spoiler
Actually, his dad(from earth) was the God of the different world. And apparently William's current family, is the desendent of the angel who looks like his son(william) which was made by god(wills dad). Which is why in the earlier chapters was described to look like an angel.
Angel's features: green eyes and white hair.
(⊙…⊙ )
So I was kinda close but not really
Ya and.... spoiler
You know how you talked about shiro being named by another worlder, hey remember the friend William was walking with right before he was hit by the truck but then was "accidentally" killed with a vase from God's beard.
OKAY EVERYONE LISTEN UP
You know how our mcs dad in his original world wasn’t around?
WHAT IF, he was also summoned to this world and our mcs current father is a descendent. Explains why they look the same!
His mother (earth) probably hated our mc cause he looked so much like his father, the man who got up and vanished (from her perspective abandoning her)
Also a long time ago shiro the dragon was probably named by another worlder (in his reminiscing the original master was in a traditional school uniform) would I be reaching if I said it could be his father from earth??
And lastly the king reminded him of his friend on earth, is this a coincidence? Or yet another other worlder and or descendant of such???