Good thread on the cumulative evidence that brain size predicts intelligence within humans, and even within families.https://twitter.com/Scientific_Bird/status/1154846441325694977 …
Correlation of IQ and overall body size (lean body mass) is much lower, like .1 or so, IIRC. And there's no principled reason to 'control for body size' when assessing brain size: https://www.primalpoly.com/s/2007-brain-size-intelligence.pdf …