Ah, good old Book of Erotic Fantasy. It's so gloriously stupid that everyone should own a copy. That table is by far not the silliest part of the book.
It's only bested by the official sex rulebook for The Dark Eye, which is an April Fools joke that spiraled out of control and has actual rules for intercourse – deliberately bureaucratic and unsexy ones included purely as a "you asked for it" joke at the reader's expense.
So basically your mitochondria decides your species?
Personally I like keeping it a little more complicated. It's the same race as the mother, unless the mother is a ditto, in which case it's the same race as the father.
At first I read this as "these species can fuck each other". Then I realized that this is only concerning conception, all these species could fuck each other as they please.
I see that nymphs bang everything, makes sense. Sprites are only slowing down (with M for Maybe) at very large sized humanoids like Giants and Ogres, that’s pretty hardcore/disturbing.
If it applies to DnD's cosmology, than it has to mean with viable offspring, because half-dwarves canonically exist in the Darksun setting and they're called Muls.
I was gonna say something about ligers and tigons, but then I did some research (looked it up on Wikipedia) and I learned some stuff. It has no relevance to my life, but it did clear up my misconception that hybrids are always sterile! So, in addition to making $125 donating plasma, making a new friend at the bus stop, and almost immediately getting drunk, I learned that some hybrids can be viable!
You sure? I believe I remember there being a story about a halfling or a gnome drinking an enlarge potion or two to get hot and sweaty with some giantess.
Technically it implies that all these other races are diverged near humans, humans being relatively unchanged remain close enough to produce viable offspring, but with different non human races being diverged from each other to the point of non viability.
So basically the racial map for a D&D setting would have humans at the center, with half children in each of the spokes of a wheel, and every non human race being nodes located in the environment where they developed in extremity, and then from there you can build the environment under the premise of the conditions that developed elves or dwarves or orcs from the human starting point.
This would also have to include a backstory spanning tens of thousands of years.
Alternative: humans were specifically engineered to be able to half-breed with anything - even elemental beings - so that they'd be able to take over the world.
Huh... never thought of that. Though I think a key difference is that it's one race diluting many races, rather than... well, in great replacement theory, it's not even whites being diluted by other races, it's them being replaced by way of high immigrations and low birth rates. So if it was like a large group of humans migrating into an elvish city, then yes, but this is more like the elvish country gaining a population of half elves and eventually humans around the edges.
From what I can tell in the wiki, great replacement people aren't so much threatened by half-minorities as they are by flocks of minorities moving in until whites are the minority. It's the culture shock, and you don't get as much of a culture shock from someone who was raised on the edges of your culture.
Not to say you have to include human hegemony in your campaign, of course. Your campaign, your rules, and you know what your players are comfortable with more than I do.