In a 2012 meta-analysis conducted by Tara Chaplin and Amelia Aldao, researchers reviewed gender differences in emotion expression from the infancy period through adolescence in order to determine the impact of development and age on gender differences. Their findings support the notion that social factors in a child's development play a large role in the gender differences that later emerge, as "gender differences were not found in infancy…but they emerged by the toddler/preschool period and in childhood".[9] One possible explanation for this developmental difference comes from the child's parents.