"Related Artists" NOT mutual? How does it work?

[Dhaka-dice]

How do "Related Artists" affect each other?

I've noticed that some artists appear in another's list but not vice versa.

The band KoRn has roughly 6 times as many plays (monthly and total) as Static-X,

but they don't even show up under "Related Artists", while Static-X is first on KoRn's list.

Does this mean that most KoRn fans listen to Static-X but not the other way around?

Suppose I make a playlist where I mix bands that have only a few listeners with bands that have lots of listeners... Who will show up in whose "Related Artists"?