Human nature is in abundance of fundamental dispositions and traits. Theories about the nature of humankind form a part of every culture. One traditional question centred on whether humans are naturally selfish and competitive. Philosophers have tried to explain human nature in its ability to behave morally and yet selfish enough to compete for more. A broader problem is that of determining which ostensibly fundamental human dispositions and traits are natural and which are the result of some form of learning or socialization. Recent research in genetics, evolutionary biology, and cultural anthropology suggests that there is a complex interaction between genetically inherited factors and developmental and social factors. Language use by humans is now generally recognized as genetically enabled, though the acquisition of any specific language also requires appropriate environmental stimuli. Behavioural differences between genders also appear to have a genetic basis, as does sexual orientation.