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Not entirely correct. There is a second gene that unfrizzles feathers. To an extent, it makes a bird with one copy of the frizzle gene look as if it is not frizzled, and a bird with two copies look as if there is only one copy present. The frizzle modifier gene is recessive, meaning that a bird must have two copies for it to impact the feathers, although the frizzling or curliness may be apparent in immature feathers. If the frizzle gene is not present at all, it has no affect.
I have heard both the the modifier is rare and that it is common. I do not know which is accurate.