Sorry, I should have phrased this better. I don't mean to say environment has no impact. What I intended to say is that the degree to which IQ is genetic vs environmentally influenced is unclear and the subject of debate. Calling environment "huge" and innate intelligence wrong is more an article of faith than a reflection of some scientific truth.
If a child was raised in complete isolation, they would have an abysmally low IQ. Studies with such disregard for human life have shown us the consequences of having one of the worst environments when growing up -- from the one I remember the children when introduced back into a normal environment never were able to learn how to communicate with another human. I would be willing to wager those children in a proper environment would be at least capable of speaking.
Perhaps my thinking is wrong or on the extreme end of the scale, but I would argue that we can extrapolate that environmental factors are a much more important factor than genetics considering various environment factors can affect genetics to certain degrees and your genes mean little to nothing in the worst environments -- only beneficial in the right environments.