They're not related, they probably grew up together to the point that they're almost as close as brothers but not exactly brothers. 
I need BL/GL recommendations
My fav BL's:
・Kiss the Abyss
・Full Volume
・Third Ending
・I can see your stats!
・New employee/recruit
・No love zone
Pfp: Camellia Cookie from CN CRK server
My fav BL's:
・Kiss the Abyss
・Full Volume
・Third Ending
・I can see your stats!
・New employee/recruit
・No love zone
Pfp: Camellia Cookie from CN CRK server