>>96887867
>going from engineered Ethereals to Tau as a whole engineered is a leap in logic.
It is and there's never been any indication of it. Even if we exclude Q'orl completely, there's still the fact that the Ethereals appeared under mysterious circumstances with lights in the sky and other shit happening, and if they hadn't, the Tau might have just eradicated each other. So it's pretty heavily implied the Ethereals have an unnatural source, whatever it might be.