You can know someone is a bad person from casual interaction, but not vice versa. There's basically no way to know if anyone intelligent is a good person without extremely intense surveillance. I guess with an unintelligent person, you can assume that they're not smart enough to hide if they're doing something really bad, but even then, maybe they're just playing dumb.
You've got to be kidding. Really, are you kidding? That's an extremely weak litmus test for goodness.
Plenty of people maintain extremely close connections with their families while engaging in activies that are terrible for the world around them. Organized criminals. Terrorists. Business magnates. Political families. Corrupt police officers. Plenty of these groups are made out of tight-knit families.
It's common, dare I say human nature, to prioritize the needs of your family. That is honorable and important, but being a Good person requires caring about strangers too.
I think you completely missed the part about living with your siblings into your 30s.
With the exception of the brothers in the mafia or brother terrorists, none of your examples would meet that standard.
Being close with your family does not mean you’re not a good person elsewhere. It does not mean you don’t care about strangers. That you’d jump to that conclusion or bring up terrorists as a counter example makes me question your own personal experiences.
All else being equal, I’d expect someone with close family bonds to the point of living with them as an adult, when they clearly have the economic means to do otherwise, as a sign of a good human. That’s been my personal experience and that’s how I see the world.