It is clear that physical traits like eye color are inherited but the human behavior is genetic or learned is more complicated. There are two separate ways in which people sort out behavior that is assumed to be not genetic from those that are assumed to be genetic. Both are heuristics, one of which is not valid, and the other is valid. Suppose, as before, there is a trait that appears to be inherited in families in such a way that it could be considered a genetic trait, in the time-tested method that "offspring resemble their parents" with respect to this trait, as Darwin noted. The second question you can ask: Is it scientific logical for this trait to be inherited genetically, or is it a more efficient way? obvious non-genetic mode of inheritance? If the trait is a physical characteristic, such as eye color, we have a biological explanation for the trait that involves the developmental process, we have some knowledge about a set of metabolic pathways that generate several molecule-like pigments. The idea that the trait is inherited is biologically sensible, so if you are unable to find all or any, of the genetic elements of this trait, you can conclude they exist somewhere. Assume, however, that the trait is a behavioral one that we see people learning in real life. Like, languages follow a similar pattern of inheritance. Most of the time, offspring resemble their parents in terms of spoken language.
The second method, the invalid one, works with an article of faith. In general, and this is an oversimplification, two basic articles of faith commonly depict the public view of genetics and shape their assumptions. Both are commonly linked with human behavioral characteristics; this can also apply to physical characteristics. One article of faith claims that humans are born with a blank slate, and that experience adds all of their behavioral qualities, such as intelligence personality, in some form or another, and so on. The other is the inheritance assumption, which states that genes affect some or all of an individual’s personality, IQ, and other characteristics. If you're a blank slate, the lack of a clear connection from genes to behavior means that your hypothesis is unrejected. If you're a genetic determinist, then the lack of such a pathway can be contributed to continuous ignorance about genes. The former may thus be expected to live in constant fear that a gene for their preferred learned behavior will be discovered, and the latter might be live in a full of arrogance, knowing and asserting a reality that is not yet known but will be in the future.
My impression is that as time goes on, there are few and fewer blank slates, and fewer and fewer pure genetic determinists out there. The reasons for this transition, in my opinion, have less to do with increased knowledge and more to do with changes in how one plays the academic game of argument, but that is a topic for another time. However, there is a risk in this shift. In the lack of any useful study, if determinists start to admit that experience and learning can also play a part and blank slates start to admit that there could be some form of the genetics behind human behavior, then we're getting closer to a simplified representation of what is actually a highly complex process. We should be gaining better-informed views, nuanced, and more complex views of how behavior develops, not simpler ones. Probably.
In general, many behavioral features have been explained in part, if not entirely, by non-genetic causes, whereas the search for the underlying genes gave no results. Throughout the 1990s, there was a lot of hope that the genetic underpinnings of human behavior would be discovered. Behavioral variation corresponds to genetic variation. However, this was questioned even before that.
