> The most common viewpoint in psych nowadays is the heredity and environmental
> factors interact to produce psychological traits and disorders.
It's the only viewpoint anyone with any understanding of genes has ever held. But it doesn't follow that questions of the form "Is the variation Xs exhibit trait Y primarily attributable to genetic or environmental differences?" are never real (i.e. meaningful, interesting, and important). Wanna know why Americans are taller today than they were a century ago? Look at the respective environments. Wanna know why I'm five inches taller than my sister?
Look at our genes (and maybe prenatal exposure to certain hormones).
-- Luke