Some of them aren't unlockable just yet. They're mostly used for in-game "content gating" - that is, unlocking or hiding content based on the user's choices. If the Quirk unlocks content you're interested in then you should get it by making choices that appeal to you naturally.
There's also a user-run Wikia (icon on the main screen of the game, up in the top-left) which I think has a list of all the currently implemented Quirks and how to get them :)