Rules-as-written, if a feat has another feat listed as a prerequisite, then you must have that feat in order to take the first feat, unless you specifically have some other ability that lets you forgo the prerequisite. This is the case no matter what the narrative justification of those feats are; being an Aberration does not inherently qualify you for Aberrant feats. In fact, by the RAW, aberrations can never take those aberrant feats, because in order to qualify for the Aberration Blood prerequisite feat, you must be of type Humanoid.
You could consider this reasonable, since if you already are an Aberration, presumably you are a specific race of Aberration which already has its own traits and qualities. The feats are there to represent the nebulous influence of some unknown Aberrant history in your bloodline, so what exactly that influence was isn't nailed down and you could conceivably have many different inherited traits. A mind flayer, on the other hand, is just a mind flayer, unless you put a template on it.
Of course, aberrations are aberrations and mutation is hardly an uncommon theme. If I were your GM, I would personally be inclined to allow characters with such matching types to take feats from the family without needing to take an "X Blood[ed]" prerequisite - it's hardly the most egregious powergaming in a game which already allows such diverse characters, and I am given to understand that the feats in such families are pretty sub-optimal choices anyway.
