Most experts agree that temperament has a genetic and biological basis, although environmental factors and maturation modify the ways a child's personality is expressed. The term “goodness of fit” refers to the match or mismatch between temperament and other personal characteristics and the specific features of the environment. Differences of temperament or behavior styles between individuals are important in family life. They affect the interactions among family members. While some children can adapt quickly and easily to family routines and get along with siblings, others who are more active or intense may have a difficult time adjusting. The interactions between these children and their parents or siblings are among a number of factors that can lead to stress and friction within the family.