By blood, I think
He DID say that the parents were only their parents by giving birth to them
blood
I havent read this yet but you mean mc and ml or someone else??
The MC and ML aren't related, but I guess the Mc's brother BY blood liked him for a long time? But I wouldn't consider it incest since the ML and MC who are the main couple AREN'T related by blood.
Not that it makes the incest less fucked up, but are they brothers by blood or are they stepbrothers?