There's absolutely no relation between one planetouched and another. You can say that there are two types of giant and that they share some sort of genetic connection(maybe), but a planetouched human something lower planar(tiefling) has no genetic connection at all to a planetouched elven upper planar(aasimar). Neither of those have any connection to genie blooded(genasi). They are all individual races. Planetouched isn't even a category in 5e, because it doesn't have to be. They're just making the various races.
So, you ignored the other 6 paragraphs I wrote. I can only assume you now accept that Giants and Dragons are races with Subraces. That or you simply abandoned the point.
So, on to the next thing. Who said anything about genetics? Do Demons have genetic material? They are energy with a personality as far as I can tell. But hey, here's a thought. Since Genetics matter... what about humans? Would Half-Elves, Half-Orcs, Muls, Human-base Genasi, Human-base Aasimar, Human-base Tieflings, Human-base Half Dragons, ect ect ect count? I mean, they all share genetic markers because they are human. That seems like a subrace situation to me.
Also, when looking for... well, every single race and subrace ever published, to try and see just how many of them cover all the ASIs (turns out elves didn't get the right bonuses) They listed "planetouched" as a racial option, with "lesser" versions of all the planetouched we've been talking about. So, seems like they WERE a race back in 3.5. My biggest issue with this search is cutting through the homebrew options, but so far it seems I gave 3.5 too much credit. They list over 22 dwarves... who are all basically identical. Same actually with the gnomes, looking at just the ASIs they are another almost 20 dwarves with strength penalties.
Weirdly, wisdom is still very hard to find. Their are 39 races with -2 wisdom, only 10 with +2, and this is with hundreds of options.