Genetic Theories

Genetic theorists assert that we can explain human characteristics, health, and/or behavior, to a significant degree, by the deoxyribonucleic acid (DNA) sequence present in the genes of a person or of a group of people presumed to have meaningful genetic similarity.

Since the beginning of the 20th century, when they rediscovered the earlier published work of Czechoslovakian monk Gregor Mendel, Western scientists have agreed that recessive and dominant factors of heredity govern numerous human traits (such as eye color). Two contributing alleles determine these traits, one from each parent, with dominant factors always physically expressed, as they have the power to mask recessive ones. Scientists call these factors genes—although this term was (and some argue still is) quite imprecise—and they conceptualize genes as clustered together on chromosomes. By the 1950s, biologists had demonstrated that the DNA within genes influences heredity, and in 1953, scientists lames Watson and Francis Crick published their famous double helix model, which is still used today, to conceptualize how discrete strands of DNA interlock with matching base pairs of adenine, thymine, cytosine, and guanine.

Today, common agreement exists that a gene is a stretch of DNA that produces a code specifying the amino acid sequence of one of the many proteins essential to the structure and function of the human body. DNA sequences in genes (the genotype) have some relationship to the physical expression of the human organism (the phenotype). However, disagreement persists about the degree of influence biological heredity has in determining who people are and how they behave. Some geneticists, biologists, and other scientists assert the dominance of a genetic paradigm in explaining human phenomena at both the individual and the societal level. Critics often argue that such assertions are greatly exaggerated and that factors such as family, natural, and social environments and economic and political structures have much more explanatory value. “Nature versus nurture” and “genes versus the environment” are frequently invoked shorthand terms for describing the tension between these points of view.

In the early 21st century, the pendulum between nature and nurture inclines quite steeply toward the former. Genetic explanations figure prominently in dominant understandings about what differentiates humans from one another as well as what determines health and behavior. Nonetheless, what is asserted by some as genetic knowledge is contested by others as genetic theory. This struggle over definitions and explanatory power is an ongoing social problem with both practical and theoretical implications.