After watching the last episodes of the season I got back to something that has been "bugging" me a little, well, not that much but when it comes to Rarity, Pinky Pie and Fluttershy I am beginning to think this thing about having different "species" of ponies in your family may actually influence some traits.
Rarity's magic is mostly what you expect from a unicorn but her innate talent to detect gems may be more in line for earth ponies, the Pie family comes to mind since they excel in practically everything mineral related.
Pinky is… uh, Pinky, I mean, she seems to have some control over reality in general, she can slide up from her secret base, she can spawn objects at will, sometimes it even looks like she has access to tech, not to mention her ability to get inside tiny spaces or even presumably teleport, this isn't even going for Pinky sense.
And then Fluttershy, she has a huge level of animal empathy, can talk to animals, even magical creatures, it even looks like she min-maxed her "earth pony" talents and almost ditched the chole weather control talent other pegasi have (all planned things aside, I know she was originally meant to be an earth pony.)