(CNN) IQ scores have been steadily falling for the past few decades, and environmental factors are to blame, a new study says. The research suggests that genes aren't what's driving the decline in IQ scores, according to the study, published Monday. Moreover, it was thought that people with lower scores would have more kids than people with high IQ scores, which would contribute to a decline in IQ scores over time and a "dumbing down" of the general population, according to Rogeberg. Researchers found that, instead of being similar as suggested by a genetic explanation, IQ scores often differed significantly between the siblings. "The interesting thing about this paper is that they were able to show a difference in IQ scores within the same families."

Source: CNN June 13, 2018 16:56 UTC