Hereditarianism is the doctrine or school of thought that heredity plays a significant role in determining human nature and character traits, such as intelligence and personality. Hereditarians believe in the power of genetics to explain human character traits and solve human social and political problems. Hereditarians adopt the view that an understanding of human evolution can extend the understanding of human nature.
Overview
Social scientist Barry Mehler defines hereditarianism as "the belief that a substantial part of both group and individual differences in human behavioral traits are caused by genetic differences". Hereditarianism is sometimes used as a synonym for biological or genetic determinism, though some scholars distinguish the two terms. When distinguished, biological determinism is used to mean that heredity is the only factor. Supporters of hereditarianism reject this sense of biological determinism for most cases. However, in some cases genetic determinism is true; for example, Matt Ridley describes Huntington's disease as "pure fatalism, undiluted by environmental variability". In other cases, hereditarians would see no role for genes; for example, the condition of "not knowing a word of Chinese" has nothing to do (directly) with genes.
Hereditarians point to the heritability of cognitive ability, and the outsized influence that cognitive ability has on life outcomes, as evidence in favor of the hereditarian viewpoint. According to Plomin and Van Stumm (2018), "Intelligence is highly heritable and predicts important educational, occupational and health outcomes better than any other trait." Estimates for the heritability of intelligence range from 20% in infancy to 80% in adulthood.
History
Francis Galton is generally considered the father of hereditarianism. In his book Hereditary Genius (1869), Galton pioneered research on the heredity of intelligence. Galton continued research into the heredity of human behavior in his later works, including "The History of Twins" (1875) and Inquiries into Human Faculty and Its Development (1883).
The Bell Curve (1994), by psychologist Richard Herrnstein and political scientist Charles Murray, argued that the heritability of cognitive ability, combined with a modern American society in which cognitive ability is the leading determinant of success, was leading to an increasingly rich and segregated "cognitive elite". Herrnstein and Murray also examined how cognitive ability predicts socially desirable behavior. They also discussed the debate regarding race and intelligence, concluding that the evidence to date didn't justify an estimate on the degree of influence of genetics versus environmental causes for average differences in IQ test performance between racial groups. Today the scientific consensus is that genetics does not explain such differences, and that they are rather environmental in origin.
Cognitive psychologist Steven Pinker, in his book The Blank Slate (2002), argues that biology explains much more about human nature than people generally acknowledge.
Competing theories
Theories opposed to hereditarianism include behaviorism, social determinism and environmental determinism. This disagreement and controversy is part of the nature versus nurture debate. But both are based on the assumption that genes and environment have large independent effects. The dominant view outside psychology among biologists and geneticists is that both of these are gross oversimplifications and that the behavioral/psychological phenotype for human beings is determined by a function of genes and environment which cannot be decomposed into a sum of functions of the two independently. And this especially because human behavior is uniquely plastic compared to that of other animals. The commonly cited heritability, h2, is meaningful only in the context of the independent effects model. This model may be a good approximation to the real function given that the range of genomes and the range of environments is sufficiently narrow, e.g., white upper middle class Americans living in Chicago. Ronald C. Bailey argues that hereditarianism is based on five fallacious assumptions. In a 1997 paper, he also wrote that "...behavior geneticists will continue to be very limited in their ability to partition the effects of genes, the environment, and their covariance and interaction on human behavior and cognitive ability."
Political implications
In 1949, Nicolas Pastore claimed that hereditarians were more likely to be conservative, that they view social and economic inequality as a natural result of variation in talent and character. Consequently, they explain class and race differences as the result of partly genetic group differences. Pastore contrasted this with the claim that behaviorists were more likely to be liberals or leftists, that they believe economic disadvantage and structural problems in the social order were to blame for group differences.
However, the historical correspondence between hereditarianism and conservatism has broken down at least among proponents of hereditarianism. Philosopher Peter Singer describes his vision of a new liberal political view that embraces hereditarianism in his 1999 book, A Darwinian Left.
