Wrong. One of those heritages gets flight: the chrysalians. The birdfolk can glide, and for everyone else (including the birdfolk), they only get actual flight if they take a gift--and the air elementaari only get non-magical feather fall and super jump, not flight, at least not until level 10.
So one out of 32/33 heritages can fly and another one gets glide, so either 3% or 6%, depending on if you count gliding as flying.
And out of (if I counted correctly) 77 heritage gifts, four grant flight. 5%.
Those are tiny fractions, IMO.