Earlier quoted context omitted.
>"But not IQ? What's the exception?" I don't think intelligence, outside of unusual situations, is a physical characteristic. So I'm not sure how to answer your question.
If you have any reasoning or research to back up your view, I would genuinely like to see it. For sure, we don't understand everything about the brain, but we certainly have found correlations between physical characteristics of the brain and IQ. BTW, try to convince a dog breeder that temperament is 100% nurture and 0% nature. I would like to hear that person's answer.
There are undoubtedly hereditary factors which will effect nurture, which will subsequently effect IQ. That is not synonymous with IQ being hereditary.
For example, there are hereditary factors which will effect career choices: temperament, physical strength, race, gender, height, and so on. Thus, career choices will correlate with genetics. That doesn't mean that career is a hereditary trait. This is an important distinction.
Likewise, twins being adopted and raised by other families does not correct for nurture. People are still treated differently depending on their genetics: temperament, physical strength, race, gender, height, facial structure, etc. As a result, seeing a correlation between intelligence in separated twins is not enough to prove a genetic cause.
Asking me to see researching backing up my view is asking me to support the null hypothesis. That's not how science works.
Wikipedia: "In inferential statistics, the term 'null hypothesis' usually refers to a general statement or default position that there is no relationship between two measured phenomena, or no association among groups. [...] The null hypothesis is generally assumed to be true until evidence indicates otherwise."
Until IQ Heritability researchers can prove that twin studies aren't just measuring nurture as a result of genetics, the burden remains on them.