Robert Plomin || How DNA Makes Us Who We Are

Genetic Traits

Robert Plomin emphasizes that virtually every psychological trait, including IQ, personality, and even television viewing, has a genetic basis. He challenges the audience to find any trait that shows no genetic influence, highlighting the significant shift in understanding since the 1970s 1. Scott Kaufman supports this by listing various traits influenced by genetics, from artistic ability to political preferences 1. Plomin's early work revealed that even traits like table manners and brushing teeth, once thought to be purely environmental, have heritable components 2.

Our psychological characteristics reflect the physical structures of our brains, and because our genes contribute to those physical structures, it is unlikely that there are any psychological characteristics that are completely unaffected by our DNA.

--- Scott Kaufman

This underscores the profound impact of genetics on behavior and personality traits.

   

Behavioral Predictions

Genetic information can predict certain behaviors, such as intelligence and alcoholism. Scott Kaufman notes that polygenic scores can explain a significant portion of IQ variance, but traditional IQ tests remain better predictors 3. Robert Plomin argues that DNA can predict educational achievement from birth, unlike other measures 3. He also discusses the genetic predisposition to alcoholism, noting that while current predictors are weak, knowing one's genetic risk can still be useful for prevention 4.

None of our predictions are ever perfect, but those are ones that we make, you know, massive decisions about, almost legal decisions in the case of drunk driving.

--- Robert Plomin

This highlights the potential and limitations of using genetic data for behavioral predictions.

   

Genetic Studies

Twin studies have been instrumental in understanding genetic influences on behavior and traits. Robert Plomin explains that identical twins, who share the same DNA, are more similar in traits compared to fraternal twins, supporting the heritability of these traits 5. He recounts the dramatic story of identical triplets separated at birth, who later discovered their striking similarities in personality and interests 6. These studies underscore the profound impact of genetics on individual differences.

Identical twins are actually more clones than clones because they are raised in the same womb and era.

--- Robert Plomin

Such findings highlight the robustness of genetic influences across different environments.

   

Nature of Nurture

The interplay between genetic predisposition and the environment is crucial in shaping behavior and traits. Robert Plomin discusses how genetic influences can shape the environments individuals create for themselves, such as children choosing to watch more television based on their genetic inclinations 7. He also critiques recent studies that claim to have newly discovered the 'nature of nurture,' emphasizing that this concept has been recognized for decades 8. Scott Kaufman adds that understanding genetic nurture can help refine how we view the role of parenting and environment in child development 8.

It suggests that the environment isn't out there happening to us. We make our environments.

--- Robert Plomin

This perspective highlights the dynamic interaction between genes and the environment.