When I'm talking about culture here, I'm referring to the anthropology sense of the word, not other usages like "workplace culture." So I do find things like art and social norms important.
Things like art and social norms certainly are important. But first of all we have canonical examples of orcs making art in The Hobbit and can presume they made more art we don’t see, and second of all, even a culture without an artistic tradition is still a culture. They still have social norms, taboos, beliefs, rituals, practices, etc. etc.
And no, I don't think it is an inherited trait, as I don't think orcs beget more orcs. At least, reading LotR that's not how it is depicted to me (I could be wrong on this). It's an evil creator that makes orcs, using evil magics. (I am specifically referring to LotR orcs here, D&D ones).
No. In the Peter Jackson movies we see Uruk-Hai being spawned out of mud pits, but canonically, the Orcs “multiplied in the manner of the children of Illúvatar,” meaning they had sex and babies just like humans do. And even in the films, Gandalf says Sarumon created Uruk-Hai by “crossing orcs with goblin-men; he’s
breeding an army.” In the books they’re a cross between orcs and humans, and Morgoth created the first orcs by corrupting elves through some unspecified process that probably involved torture, forced breeding, and yes, probably magic.
It’s worth noting that Tolkien was never entirely comfortable with this explanation because he rightly realized that it was pretty yikes to say a race of people is inherently evil because their ancestors were the
victims of atrocity. But he didn’t come up with an alternative explanation in his lifetime. He just wasn’t able to reconcile his desire for orcs to be inherently evil with his desire for evil to be incapable of creation
ex nihlo. If evil can only corrupt the creations of good, evil can’t be inherent to the nature of any created being, and try though he did, Tolkien never managed to resolve this dilemma.
Well, a gnoll is created through fiendish magic. If you read their origin story in the MM;
Demonic Origin. The origin of the gnolls traces back to a time when the demon lord Yeenoghu found his way to the Material Plane and ran amok. Packs of ordinary hyenas followed in his wake, scavenging the demon lord’s kills. Those hyenas were transformed into the first gnolls, parading after Yeenoghu until he was banished back to the Abyss. The gnolls then scattered across the face of the world, a dire reminder of demonic power.
It is hard to imagine a creature born in this way to suddenly realize the different between right on wrong.
I don’t see why the method of their creation story matters. In a lot of real-world myths humans were originally created from mud or clay, but we accept that humans aren’t immutable. So what if gnolls were created when some hyenas ate some demon flesh, if they’re sapient beings they should be capable of understanding right and wrong, shouldn’t they? And if they’re not sapient beings, why are they humanoids instead of beasts or fiends?
Gnolls are actually more similar to fiends like demons than anything made through normal reproduction. I'll add as it isn't explicitly said above, more gnolls are made by hyenas feasting on what gnolls have killed.
Yeah, if you make them fiends, fine. I don’t think they should be fiends, they’re native to the material plane and seem to exhibit humanoid thought processes, but if you really must have evil gnolls, then make them fiends. I’d say the same of orcs.
Eberron runs gnolls a little differently, as they somehow cut off ties from their demon lord. But I see no reason why it is problematic that creatures born of fiendish magic are evil, as it has nothing to do with biology at all.
Biology is a red herring here. We’re talking about a fantastical world where gods provably exist and regularly meddle in mortal affairs, magic is real, and most myths are literally true. Biology as we understand it probably isn’t even a thing. The issue is the implication that evil is an
inherent trait, passed along bloodlines. That the information is not passed by genes is completely irrelevant.
If we say gnolls in this depiction are problematic, that would make fiends themselves problematic, and then... well, I won't go into that.
Gnolls
aren’t fiends though. If they become fiends in 6e or in a mass errata, I’ll begrudgingly accept that they’re always evil, but unless and until that happens, it’s exactly the same problem as always-evil orcs.
As to whether or not fiends being always evil is problematic, I don’t think they are personally, but I concede that there are some pretty strong arguments one could make that they are. But, I think they’re fine because the nature of outsiders is that their natures are defined by their alignment, rather than the reverse. If a devil stops being evil, it stops being a devil.