Using genetics to understand human behavior
WEST LAFAYETTE, Ind. – Humans contain multitudes. Every person on the planet contains enough DNA to stretch back to Pluto – several times over.
Studying how all this genetic material works, and especially how genes influence human behavior, is an extremely complicated task – one that is being made easier by the emergence of huge genetic databases and complex data science analysis techniques to analyze these data.
Robbee Wedow, assistant professor of sociology and data science in the College of Liberal Arts at Purdue University, one adjunct assistant professor of medical and molecular genetics at the Indiana University School of Medicine, and Purdue’s inaugural faculty-in-residence at AnalytiXIN/16 Tech in Indianapolis maps these miles of genes to gain insights into how genetics interact with social forces and environments. It uses genetic databases to study how small pieces of genes called single nucleotide polymorphisms, or SNPs, affect complex, wide-ranging traits, including sexual behavior, educational level, socioeconomic status, health behaviors and more.
“We know that social forces, such as socioeconomic status, play a role in influencing a person’s life and life outcomes,” Wedow said. “But we also know that there is a genetic component to every behavior. What we don’t yet understand is how these biological forces interact with the environment and what these types of interactions might mean for the social sciences – and what we think we know about social science research to date. We are using rich genetic data to make social science more accurate and replicable and to explore what might be possible at the intersection of genetic and behavioral science.”
When scientists sequenced the first human genome in 2003, the true scale of genetics began to become apparent. Early geneticists thought that finding a gene for each trait was simply a matter of looking in the right place.
However, the bases of DNA and genes are not simply keys on a huge piano on which human lives are played like masterpieces. Instead, DNA works more like a pipe organ, where stops, switches, and pedals can change the way notes sound, mute them, or increase their volume. Environment, nutrition, pollution, life experiences, and other circumstances can change when and how genes are important for certain outcomes, and even change which locations in genomes are important for those outcomes. There is no single gene for a behavioral outcome. Biology is not destiny: it may define the musical score, but musicians are free to improvise and interpret as they play.
The idea, Wedow emphasizes, is not that these genes control a person’s life or destiny. Each SNP, in fact, has a very small effect on an overall outcome, such as educational attainment. No “Gattaca”-level reading of someone’s destiny from their genes – in the style of the 1990s dystopian film – is on the horizon. Instead, being able to clarify the genetics of certain behaviors could help scientists understand the nuances of human behavior.
“People think genetics is always about biology, but in the case of sociogenomics it’s more about taking advantage of this new, well-resourced data to better understand one’s own results, or about enabling researchers to do social science and more accurate behavioral research. ,” Wedow said. “The social sciences have recently struggled to replicate studies. Sample sizes are often too small for accurate estimates and certainty. This is where the potential for using these huge genetic databases for social sciences comes in. They help us to have a much clearer and safer vision of what is really happening.”
Analyzing genetics is just the first step. An American geneticist in the early 1800s might have correlated genetics with educational attainment and concluded that anyone with two X chromosomes tended to be less educated. This does not happen because chromosomes have anything to do with education. On the contrary, the correlation reflected social and gender prejudices present in the culture of the time. Similar insights are hidden in Wedow’s research.
“Sociogenomics is not necessarily about biology, as some might think,” Wedow said. “When someone studies cancer genetics, they are studying it because they want to elucidate the biology of cancer; they want to discover ways to better diagnose, track and treat it. But researchers in the field of sociogenomics want to study genetics to make better social sciences. No one would ever study sociology without considering socioeconomic status and the environment. We want to be able to take genetics into account in the same way.”
In a study in volume 7, no. 7 of the journal Nature Human Behavior, Wedow, his co-author Andrea Ganna of the University of Helsinki, and their other co-authors analyzed 109 research questions in more than 300,000 individuals to examine the ways in which human genes people correlated with whether they answered certain questions or left them blank in surveys completed in the UK Biobank. This may seem quite obscure, but it fills a gap that the field of sociology has struggled with for decades.
“How do you know what you don’t know or how could someone have answered a question if they chose not to answer it?” Wedow said. “It turns out that the genetics of people who do or do not answer the survey question overlap with the genetics of other outcomes, such as education, income, or certain health behaviors.”
This means scientists can use this type of data to better understand how people who choose not to respond to questionnaires may also share similar responses to questions about health or social behaviors. Geneticists can also use the results of this study to correct biases in genetic studies of any behavioral, psychiatric, or medical outcomes.
“We still cannot divide the signal from the noise or causally separate the effects of the environment from the effects of biology,” Wedow said. “We know that genetics correlate with certain outcomes, but we are not at a point where we can say that any specific gene causes any outcome. The effect of each individual gene is small. It is only in large data sets that we begin to gain the statistical power to obtain meaningful and reproducible results. We are using these exciting new data and emerging tools to revolutionize the social sciences.”
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Source: Robbee Wedow, firstname.lastname@example.org