The biological roots of gender differences interact with the social environment in various ways. Biological theorists propose that females and males have innate differences that exist at birth, but unfold with age and maturation in response to interactions with their specific environments (Chaplin & Aldao, 2012).[1] An important argument for this viewpoint is that "gender differences in emotion expression are the result of a combination of biologically based temperamental predispositions and the socialization of boys and girls to adopt gender-related display rules for emotion expression".[11] It has been suggested that even infant males display higher levels of activity and arousal than do infant girls as well as a lower ability for language and behavior inhibitory controls, which are biologically-based characteristics.