Okay, hear me out....crazy theory time.
What if gen is a more good of guy then he lets on and somewhere in the past mc's dad(who seemed quite a abusive person) tried to beat mc and gen saw it in doing so accidentally killed mc dad to protect mc. Now the mom dead eyes make sense and she put that under wraps with condition being mc getting a job under Gen's father company for her easiness. So begging to them to get mc a job might actually have been a threat or else type of situation.
Because of that Gen now takes his angry out on mc every chance he gets. And thinks he has a claims on his life because of all the trouble he got into dealing with his family.