There is a world of difference between "is a physical trait" and "is attached to, associated with, or correlated with physical traits". The way I see it, saying that intelligence is correlated with physical body features is admitting that intelligence is not a physical trait itself after all.
The first reason I insist on the difference is because absolutely everything indirectly depends on physicality of the biological body. Spirituality aside, there isn't a single thing about humans that doesn't depend on the shape or size or chemistry or electrical charge of something somewhere. This makes "physical trait" an utterly useless category, one that clearly includes playing piano, and I really don't like that.
The second reason I insist on the difference is because the correlation doesn't have to be linear. There's no reaso why it can't be quadratic or logarithmic or exponential or hyperbolic or whatever. Being a literal physical feature imposes normal distribution with tight variance. Merely being correlated does not. If you still want to argue geniuses are not that much more intelligent than average people, you'd need more evidence than simple hereditability.
When you say "intelligence is a physical trait", I hear "there is a part of parts of the brain that have a certain total volume/mass/density/number of neurons/synapses/neural pathways/etc., and that number is the literal definition of intelligence". It's how it works for every other thing that we call a physical trait. If you didn't mean it like that, maybe you should have used a different terminology from the get go.
Now excuse me while I go looking for 10-15 more citations on the genetic component of musical ability that you're definitely not going to dismiss as irrelevant for one reason or another.