Calling something "controversial" is a total non-argument. The book's science about IQ is solid.
In actuality, the content of the book was simply a collection of mainstream scientific consensus ideas at that time, without specific controversial add-ons. It's only after the book was published, the book unexpectedly was attacked by proto-woke people.
Inventing strawman out of thin air in order to drown discussion, to attack individuals and paint them evil, that's literally what Nazis did. How ironic.
In actuality, the content of the book was simply a collection of mainstream scientific consensus ideas at that time, without specific controversial add-ons. It's only after the book was published, the book unexpectedly was attacked by proto-woke people.