This being fiction and not reality, the dwarfish ability to build underground structures is actually literally innate. Not genetic perhaps, but somehow bound to

This being fiction and not reality, the dwarfish ability to build underground structures is actually literally innate. Not genetic perhaps, but somehow bound to dwarves racially. Remember this is the same game that prohibited halflings from being magic-users (well, it used to. I haven't read 5th ed). Whatever the reason, the game presents certain abilities as actually being racially innate. It's not reality. It's a fantasy world. Additionally, it's a literary fantasy world. Real-world concepts of race don't apply. If you think it's a terrible concept, by all means play a different game, build your own world, whatever. But just because the author doesn't like D&D doesn't mean it's wrong.