Why even 100% genetic traits might be changeable, even without gene editing.

Almost everything about you is known to be at least somewhat influenced by your genes. Most of your traits are at least somewhat predictable by knowing your relatives’ traits, even if you each grew up in different environments, with the predictability rising the closer your relative is.

A few conditions are completely inherited, like sickle-cell anemia or cystic fibrosis, where the genetic factors are known and the inheritance is entirely predictable. In these conditions, if you have such-and-such a gene (or in the case of these recessive disorders, two copies of such-and-such a gene), then you will always have the condition (and if you do not have the appropriate gene, you will never have the condition). Anyone who’s been through a high school biology class has at least some vague familiarity with this idea.

More often, however, genetic factors are fuzzier. Height, for example, is very heritable, but knowing the heights of your parents does not let us compute an exact distribution of possible heights for you. In these cases, we have to evaluate how heritable a trait is by comparing cousins to siblings to identical twins and employing some mid-level statistical techniques.

Many traits that we think of as being the results of our own choices are, in fact, quite heritable. One study finds, for example, that about 50% of the variance in political beliefs can be explained by someone’s genetics. Height is even more strongly linked to genetics, with some 90–95% of variance in height explained by genetic factors.

All of this is perfectly sound science and mathematics. Unfortunately, it is often grossly misinterpreted.