Yes, I was one of THOSE kids. Anyway, Nethack for some reason reminded me of game rules and I realized something. As you nerds will recall, in Dungeons and Dragons characters can be half-elves or half-orcs. Now, in my later education I was made aware of Linnaean classification and viability and such things. So, hence, now either the ‘races’ of half-orcs and half-elves are sterile, like mules or that lion-tiger mix, or (drum roll) humans and elves and orcs are all of the same species. Ohmygod!
I clearly need a hobby.
Or…magic screws with genetics, making cross-breeds viable.
Heck, if you accept that a creature like a centaur is even possible, then I think you also have to accept that genetics works a bit differently in fantasy than in reality.
Looks like somebody missed their saving throw. You’re messing with the underlying principle of D&D and that is to suspend disbelief. Luck for you I can solve that with one whack from my +2 rod of enchantment 
In my campaign humans are the only race that can crossbreed with the other demihuman and humanoid races because they are their ancestors and divergent evolution has made the elves, dwarves, orcs, etc. too different from each other to breed - but they all are close enough to their human ancestors to produce offspring (though not always fertile offspring). This has been a source of great worry for the demihuman races since humans were re-introduced to their world, as they fear that in time the only traces of their races will be slightly pointy ears or largish canines on otherwise-normal humans. Yep, I have trouble kicking realism from my fantasy, I’ve managed to rationalize a mostly typical 3E D&D setting into a far-future science fiction setting.
In AD&D 2nd edition they had a campaign setting called Dark Sun. Any way in this setting one could make a human/dwarf hybrid that would be called a Mule. He was also sterile.
Marc
In Tolkein’s mythology, Melkor created orcs by magically corrupting a captured tribe of green elves.
Also, elves and humans are cross-fertile, and their offspring are fertile. Interestingly, a half elf must choose to be immortal, like his elven parent, or to have a soul, like his human parent.
Did you read today’s FoxTrot?
I think they’re sterile. Think about it, have you ever played a quarter elf? They aren’t mentioned.
Ooh! Ooh! Time to show my geekdom!
The naming rules between Elves and Humans are something like this:
If you’re of 100% Elvish ancestry, you’re an Elf
If you’re between 50% and 99% Elvish, you’re a Half-elf
Otherwise, you’re a Human
The fact that those numbers even come up (although I must admit I don’t remember where I read them) indicates that Half-elves, at least, are not sterile.
I’d have to agree that it’s magic influencing genetics. One plausible explanation is that the races are all magically created deviations from a single common ancestor. They can cross breed, but the ratios must be just right to keep the properties of the more mythic breeds.
I’d guess that humans would be the base race since you never hear of an elf-dwarf or some such. But I’ve never played D&D.
~Matt
Actually, the 3e PHB includes mention of Second Generation Half-Elves - 2 half-elf parents, a half-elf parent and a human parent, or a half-elf/elf’s kid.
I, personally, think the biggest reason there’s no Elf/Dwarf hybrids is the fact that Elves and Dwarfs typically hate eachother.
Magic definitely has a thing to do with it - Dragons are cross-fertile with almost all creatures for heaven’s sakes!
But they ARE referred to as Races rather than Species, of course.
And the non-humans are called Demi-humans…so Humans seem the base race…
::Decides not to get into the bloodline blending of his most recent campaign…9 characters managed to get about 15 different races represented…::
In the Dark Sun campaign setting for AD&D we learn that humans and dwarves are cross-fertile, but the offspring are sterile. Since humans and dwarves find each other sexually unattractive, the only half-dwarves are the children of slaves who were forced to breed (dwarf-human hybrids are extremely tough and actually bigger than a normal human, make great laborers or gladiators).
I heard somewhere that in the Greyhawk campaign setting background humans are the result of orc/elf crossbreeding, which is why orcs and elves never mate anymore - both races consider humans a HUGE mistake.
I’ve never heard that before…Not that I delve too deeply into the origins of the species usually.
Scaaaaaary thought…
(But, yeah, most orc and many elves would definitely consider humans a mistake. The number of half-elves would seem to indicate it’s not that common an attitude among the elves…)