No I'm not. Not as stated.
You are correct in that the more trainable intelligence is, the less people care about IQ. Coincidentally, people's caring about IQ has been falling drastically the last couple decades.
> What is a naturally gifted child prodigy, if not evidence of physical traits?
It's evidence that it's not a physical trait at all. At least not the kind that scales with size (and therefore would have a relatively narrow variance among adults with both the median and the modal value in the dead center between 3rd and 97th percentile, while undergoing a massive change around the time of puberty, so much so that reaching average post-puberty score before puberty is near impossible).
Obviously everything ultimately comes down to neural connections powering the brain. Knitting, bull riding and playing piano are just as much physical attributes as intelligence. We live in a physical world after all. But that makes the term "physical trait" quite useless. So instead, I'm choosing to interpret physical trait as anything that is almost entirely determined by measurable aspects of a person's physical body. And intelligence just isn't it.
Did you mean to say "intelligence is primarily genetic" instead? That I would agree with.