The expression nature vs. nurture describes the question of how much a person's characteristics are formed by either nature or nurture. Nature means innate biological factors (namely genetics ), while nurture can refer to upbringing or life experience more generally.
How Genetic and Environmental Factors Are Identified
Modern scientific methods have allowed researchers to advance further in understanding the complex relationships between genetics, life experience, and psychological characteristics, including mental health conditions and personality traits. Overall, the findings of contemporary studies underscore that with some exceptions—such as rare diseases caused by mutations in a single gene—no one factor, genetic or environmental, solely determines how a characteristic develops.
Scientists use multiple approaches to estimate how important genetics is for any given trait, but one of the most influential is the twin study. While identical (or monozygotic) twins share the same genetic code, fraternal (or dizygotic) twins share about 50 percent of the same genes, like typical siblings. Scientists are able to estimate the degree to which the variation in a particular trait, like extraversion , is explained by genetics in part by analyzing how similar identical twins are on that trait, compared to fraternal twins. ( These studies do have limitations, and estimates based on one population may not closely reflect all other populations.)
It’s hard to call either nature or nurture genes or the environment more important to human psychology. The impact of one set of factors or the other depends on the characteristic, with some being more strongly related to one’s genes—for instance, autism appears to be more heritable than depression . But in general, psychological traits are shaped by a balance of interacting genetic and non-genetic influences.
Both genes and environmental factors can contribute to a person developing mental illness. Research finds that a major part of the variation in the risk for psychiatric conditions such as autism spectrum disorder, anxiety disorders, depression, and schizophrenia can be attributed to genetic differences. But not all of that risk is genetic, and life experiences, such as early-life abuse or neglect, may also affect the risk of mental illness (and some individuals, based on their genetics, are likely more susceptible to environmental effects than others).
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