sweeping statement, I understand. at core is my position as a materialist - I think everything is physical / material / biological. 'Intelligence' is simply an expression of that, and IQ as a measure of that is measuring something that's biological, like left-handedness or height.

My evidence... I've not seen any evidence to the contrary. We do see evidence that physically messing with brains causing changes in brain function. Brain damage can cause impairment to memory - short term memory is one of the elements of IQ that gets measured in tests that I've taken.

If you have evidence to the contrary that what we measure as IQ is somehow not rooted in biology, please share it.

I'm not here to prove the negative. Your opinion that nurture does not exist hand-in-hand is false.

"everything is physical / material / biological."

I don't believe in ghosts/souls/the immaterial, but this is irrelevant to social conditioning having an objective effect on IQ tests. Yes, the brain that stores information is "physical", but the information is not stored in birth.