User blog comment:Phantombeast/Quick Question/@comment-4728047-20140211023251

well, there could be some element of genetics involved (example, all the Strauss siblings know Take Over), though that could also be seen as an affect on your internal Eterano by the Eterano you're exposed to on a daily basis (example, Dragon Slayers have all been exposed to a Dragon's natural Eterano, and therefore learn Dragon Slayer Magic and can take on the properties of a Dragon, but that's just speculation isn't it?)

but it's probably more like what Ash says and that your Eterano doesn't take any particular shape/form until you start applying it in certain ways (like a lump of clay, waiting to be shaped into a vase or something)

however, everyone's different and there are probably some out there who's Eterano is the way you stated in the blog

alas, however, as we are not magically gifted beings, we may very well never truly know, will we?