The behavior of parents with their children has a direct effect on their development. A recent study suggests that the support a mother provides can influence her child's level of intelligence. Intelligence is shaped by multiple factors, including genetics and environment. According to a theory developed by American clinical psychologist Ronald Wilson, the heritability of IQ — the extent to which intelligence is inherited — increases as a person ages. In early life, a child's intelligence is more influenced by the shared environment of the household. As the individual grows older, genetic factors become more significant. Researchers Curtis Dunkel, Dimitri van der Linden, and Tetsuya Kawamoto have focused on the original environment in their latest study, examining how maternal behavior affects a child's intelligence. Their findings were published in the review Intelligence. The study looked at three aspects of maternal behavior. To conduct their research, scientists analyzed data collected between 1996 and 2010 from the Early Head Start Research and Evaluation Study. The final sample included 1,075 children from diverse backgrounds. To measure maternal support, researchers used a semi-structured game called "the 3 bags task." Families participated in this exercise when the child was 14 months, 24 months, and 36 months old. During the game, researchers observed three aspects of maternal behavior: parental sensitivity, cognitive stimulation, and positive consideration. From 14 months to 10 years of age, the children were tested on their cognitive abilities to measure their general level of intelligence. Researchers also assessed the intelligence of the mothers. The study found a positive association between maternal support and the child's general intelligence, even when accounting for the mother's own intelligence level. "Maternal support influences general intelligence at the beginning of life," concluded Curtis Dunkel in an interview with PsyPost. The researchers noted that this effect tends to fade in adulthood. However, they also found that the link was weaker when the children's temperament showed an interest in their parents' efforts to stimulate their thinking. Despite this, maternal support still had an influence on the child's intelligence.