Children in the U.S. are more severely affected by income differences than children in most developed countries, according to an article published by a UT researcher. 

The study focused on the development of nearly 25,000 pairs of siblings and twins across several developed countries, such as the U.S., Germany and Australia. It was published in Psychological Science last month by UT associate psychology professor Elliot Tucker-Drob and co-author Timothy C. Bates from the University of Edinburgh.  

Over the years, scientists have argued whether a child’s genetics or environment determine the child’s intelligence. One theory, called the Scarr-Rowe hypothesis, argues that the socioeconomic status of a child influences the extent to which genetics influences intelligence.

Psychologist Eric Turkheimer compared students in the study to flower seeds, according to an interview with Ars Technica. Those seeds inherit genes from their parents that make them tall or short. If the seeds are planted in a nutrient rich soil, the flowers will grow to different heights, depending on their genetic variation. But if the seeds are grown in a poor, sandy soil, all the seeds’ growth will be stunted. 

After organizing the data by location, the authors found that impoverished children in the U.S. did not usually do as well as their higher-income counterparts, regardless of genetic potential. This, however, was not the case in the other countries.

The authors speculated that access to high-quality public education and health care in Western Europe and Australia play a role in helping their students avoid the pitfalls of poverty. 

In the United States, schools are publicly funded, so some schools have less funding just because they are in a low socioeconomic area, said Ashley Murphy, a STEM education graduate student. Murphy said that low socioeconomic schools tend to have fewer resources, including teachers, textbooks and technology, compared to schools in higher socioeconomic areas.

Murphy said standardized testing in the United States could be another reason why students underperform.

“A big glaring difference between us and many other countries is the amount of high stakes testing and the way that we do it and the type of high stakes testing,” Murphy said.

Students coming from higher income families may be able to afford to attend private schools that are able to set their own curriculum.

“Rather than learning fully one idea, they are expected to know many small things about tons of different ideas that doesn’t always lead to understanding,” Murphy said. “To make [student performance] better … I would get rid of the high stakes testing.”