Effective altruism is based on the core belief that all people count equally. We unequivocally condemn Nick Bostrom’s recklessly flawed and reprehensible words. We reject this unacceptable racist language, and the callous discussion of ideas that can and have harmed Black people. It is fundamentally inconsistent with our mission of building an inclusive and welcoming community.
— The Centre for Effective Altruism
Okay, if there's anyone here who actually believes in HBD, here's a couple reasons why you shouldn't:
Human biodiversity is actually pretty low. Homo sapiens has been through a number of bottlenecks.
Human migrations over the last thousand years have been such that literally everyone on Earth is a descendant of literally everyone that lived 7000 years ago whose offspring didn't die out. This is known as the Identical Ancestors Point.
Africans have more genetic diversity than literally every other ethnicity on earth taken together, so any classification that separates "Africans" from other groups is going to be suspect.
Race isn't a valid construct, genetically speaking. It's not well defined. Most of the definitions are based on self reports or continents of origin, when we know what is considered "black" in the US may not be so in, say, Brazil, or that many people from Africa can very well be considered "white".
Intelligence is not well defined. There's no single definition of intelligence on which people from different fields can agree.
IQ has a number of flaws. It is by definition Gaussian without having appeared empirically first and the g construct itself has almost certainly no neurological basis and is purely an artifact of factor analysis.
Twin studies are flawed in methodology. Twins, even identical twins, simply do not have exactly the same DNA.
Evolution isn't just mutations and natural selection. Not every trait is an adaptation.
Heritability does not imply genetic determinism. Many things are heritable and do not involve genes. These include epigenetic mechanisms, microbiota, or even environmental stress on germinal cells.
We don't mate randomly, which is an assumption in many genetics studies.
HBD is not generally accepted in academia.
Many public HBD figures have been found guilty of fraud. Cyril Burt would literally forge results, while Lynn would take the average of two neighboring countries' IQ in order to derive "data" from a country's unknown national IQ.
Special thanks to these threads for compiling most of the information
Now you might want to attack one of these (and feel free to send me a message), but even if you're right, that would still leave more than enough reasons to stay away from HBD.