I. One of the scientific debates I try somewhat to keep up with is the so-called “nature versus nurture” debate, the debate as to whether and to what extent individual traits and abilities are determined by our biology (which is what I will use as for a catch all for genes and whatever other mechanism may be supposed to be doing this work) or by our environment, which is supposed to include all mechanisms other than those that are intrinsic to our individual biology, including our upbringing, what we are taught, and our social life.
Note that this question of biological versus environmental determination is different from the question of the heritability of individual traits and abilities. The heritability of a trait is the ratio of biologically caused variation to total variation of that trait within a specific population. Heritability is often used to support arguments that specific traits are biologically determined. But, as Ned Block carefully shows in his classic article on the matter, that a trait is heritable does not by itself entail that it is biologically determined, and this means that other (often highly controversial) background assumptions and arguments are required to make this step. The question of the heritability of a trait needs, therefore, to carefully be pulled apart from the question of whether it is our biology or the environment that actually determines an individual’s traits in a given situation.
There is no need, however, for you to understand heritability, as it is only the latter question I will be concerned with here, the biological versus environmental determination of human traits and abilities. However, what follows is not a direct intervention in this debate, but rather, a modest intervention into its supposed stakes for the lives of individuals, and how we conceive of those lives.