By Robert Hazen, George Mason University
To understand behavioral genetics, we have to make three critical assumptions: we can quantify behavior, we can identify environmental factors, and we can determine genetic factors. If all three assumptions of behavioral genetics are realized, we can perform statistical tests, and they may be able to establish definitive links between heredity and certain kinds of personal traits.
First Assumption
The first assumption is that behavioral and personality traits can be ranked, at least in some sort of qualitative way. For example, behavioral researchers generally agree that personality rests on five broad traits.
The first is called extroversion; that’s whether one is outgoing, or decisive, or persuasive, for example. The second trait, according to behavioral geneticists, is neuroticism; it includes the traits of being emotional, irritable, or anxious. The third trait is conscientiousness; that’s whether one is organized, practical, dependable. Then comes agreeableness—is one good-natured, is one warm, is one kind? Finally, the fifth trait is openness: curiosity, insightfulness, imagination.
To one extent or another, each of us displays a combination of these five traits, and the assumption is that we can have some qualitative ranking of individuals, a 1-to-10 scale of people and how they fit into each of those five characteristics. Let’s assume that similar rankings are possible for different kinds of intelligence: for example, music ability; memory; spatial reasoning; and verbal ability. Although I think all people agree that a single number for IQ is meaningless. That’s the first assumption, that we can rank these characteristics.
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Second Assumption
The second assumption of behavioral genetics is that environmental factors influencing behavior can also be identified. There are many of these factors, and it’s difficult to identify them all. They can include things like nutrition, exposure to drugs, sleep patterns, stress; those are all well-known to affect behavior.
However, there are also other influences that may be quite subtle, such as visual stimuli when one is in infancy; pollutants in air and water; exposure to sunlight; all types of physical activity etc. These may be much more subtle and difficult to track down, in trying to figure out relationships to behavior.
Third Assumption
The third assumption is that distinctive genetic characteristics of individuals can be quantified. While this is unambiguously true; whether we can make a correlation with behavior is not so necessarily true.
However, the day is going to come when the entire human genome can be sequenced automatically, perhaps in a matter of a few days. Rather than having a single human genome, which is what’s envisioned by the Human Genome Project, we’re going to have access to thousands of different human genomes and individuals, and each of those is a detailed chemical map of a unique individual.
Imagine that we map the genomes of a hundred gifted musicians, and maybe a hundred people who express that they’re tone-deaf, they can’t even carry a tune. We might then see that there are certain combinations of genes that are always present in the musicians, and not present in the people who are tone-deaf. While we don’t know if that’s going to happen or not; but the fact is, in some years we will be able to do a test like that, and perhaps we’ll be able to identify musically gifted children at birth. Whether we want to do that is a different question.
Ethical Implications
Scientists, and the public at large, are strongly divided over these ethical implications of genetic testing. Proponents see this research as the best hope for understanding and ameliorating antisocial behavior. If genetic traits influence behavior, then improving a child’s environment represents our only realistic hope of helping out the children. We can’t change their genes—well, maybe we can—but changing the environment is something society can do, and maybe that’s our responsibility.
If, on the other hand, one adopts a more conservative agenda, then findings of behavioral genetics might be equally assuring. What one might say is that genetic traits absolve society of responsibility for things like poverty, for crime, for drug abuse; society can’t take responsibility because it’s an individual genetic thing, and so it’s not an environmental question, they will say.
Genetic racism is by far the scariest of the scenarios here. If we can in fact identify certain genes, and then discriminate against people because they carry or they don’t carry a certain gene, that becomes the scariest possibility of all. Behavioral genetics forces us to confront the fact that we are, in essence, chemical beings.
We are vastly complex, we’re adaptable, unique, we’re unpredictable, to be sure; but we’re still chemical beings, and those chemicals are determined by our genes. We’re learning to identify those chemicals; we’re learning to decipher how they’re made, we’re learning to discover what they do, and even how to fix them when they’re defective. In the process, science, once again, has forever changed the way we think about ourselves, and about our place in the universe.
Common Questions about Behavioral Genetics
The three critical assumptions we need to make to understand behavioral genetics are: first, that we can quantify behavior; second, that we can identify environmental factors; and third, that we can determine genetic factors.
Behavioral researchers believe that personality rests on five broad traits. The first is called extroversion; that’s whether one is outgoing, or decisive, or persuasive, for example. The second trait is neuroticism; it includes the traits of being emotional, irritable, or anxious. The third trait is conscientiousness; that’s whether one is organized, practical, dependable. Then comes agreeableness—is one good-natured, is one warm, is one kind? Finally, the fifth trait is openness: curiosity, insightfulness, imagination.
Genetic racism is the discrimination that may take place when scientists identify certain genes, and then discrimination occurs against people because they carry or they don’t carry that particular gene.
