The more relevant point is additive heritability (aka h^2 or narrow sense heritability.
Not all traits are additively heritable, e.g., the malaria protection/sickle cell anemia gene, and in particular its not obvious that intelligence is additively heritable. One theory I've heard is that things like autism are a result of having too many "intelligence genes".
Even in the most extreme case of dominance, where H^2 greatly diverges from h^2, the additive heritability is not zero. (But if you had a trait in which heterozygotes were distinguishable from homozygotes, but the two types of homozygotes were not distinguishable, then h^2=0. I know of no such trait.)
A long blog post explains why the author, a feminist, is not comfortable with the rationalist community despite thinking it is "super cool and interesting". It's directed specifically at Yvain, but it's probably general enough to be of some interest here.
http://apophemi.wordpress.com/2014/01/04/why-im-not-on-the-rationalist-masterlist/
I'm not sure if I can summarize this fairly but the main thrust seems to be that we are overly willing to entertain offensive/taboo/hurtful ideas and this drives off many types of people. Here's a quote:
The author perceives a link between LW type open discourse and danger to minority groups. I'm not sure whether that's true or not. Take race. Many LWers are willing to entertain ideas about the existence and possible importance of average group differences in psychological traits. So, maybe LWers are racists. But they're racists who continually obsess over optimizing their philanthropic contributions to African charities. So, maybe not racists in a dangerous way?
An overly rosy view, perhaps, and I don't want to deny the reality of the blogger's experience. Clearly, the person is intelligent and attracted to some aspects of LW discourse while turned off by other aspects.