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 . 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. They have avowedly rejected the standard social science model.
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.
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. In individual cases, hereditarians believe that genes play an intermediate role, while genes largely determine the differences between the human races and genders. In all cases, they believe this is an empirical and not a philosophical question.