Genetic determinism

Genetic determinism is the mechanism by which genes, along with environmental conditions, determine morphological and behavioral phenotypes.

The term genetic determinism has sometimes been alternatively applied to the unscientific belief that genes determine, to the exclusion of environmental influence, how an organism turns out: this is now more often called biological determinism. Such views have sometimes been attributed to opponents, or forwarded in hypothetical arguments, without having been actually held by anyone: as CH Waddington wrote in 1957, "It is of course a truism which has long been recognised that the development of any individual is affected both by the hereditary determinants which come into the fertilised egg from the two parents and also by the nature of the environment in which the development takes place."

The use of genetic determinism in this sense of an accusation of holding unscientific beliefs originates in the historical "nature versus nurture" dispute, especially during the 1970s and 1980s.

A related error is the supposed misconception holding that geneticists and molecular biologists have only recently come to the realization that environment is essential in the development of the organism from egg to adult. It was understood long ago that genetic effects cannot be studied in isolation of the environment and that all measurements of such effects are only relative to stable external conditions. Also known since at least the 1950s is the means by which the environment influences embryonic and juvenile development, namely the epigenetic control of gene activation and deactivation.

Genetic determinism, which identifies the gene as the biological source of morphology and instinct, can be traced back to Austrian theorist August Weismann, who proposed in the 1890s that the key actors in the struggle for survival are not organisms but their genes, which he called determinants. While Darwin's concept of natural selection was intended to apply to whole organisms, Weismann modified Darwin's idea according to a process he called "germinal selection." Since the fittest determinants would be whichever ones correlate to the most useful phenotypic traits, germinal selection would result in the fittest organisms surviving and reproducing. Weismann referred to the chemical carrier of these determinants as the germ plasm, now known to be DNA.

...
Wikipedia