Simplified Mendelian inheritance? Neat.
But I think you are ignoring a vital fact... dominant-recessive genetics aka the first law.
The whole Apple family is Earth unicorns for example, though I confess you granting them pure earth pony genes does account for that. But Pinkie's recessive unicorn gene for example should also lead to unicornian family members after some time.
Still, one might claim that genetics does work in a different way in Equestria, just like physics does.
Scarim Coral said:
As for the OT it's interesting althought where would Prince Blueblood, Princess Celestria nephew would fit into the chart?
He's a dubious character anyway. Celestia's
nephew... that'd mean he's either Luna's son or there is an unknown sibling that's never mentioned.
I say he's adopted!
Did someone already discuss that topic in the group? I'm not active enough to know everything that's being said in there.