Sex-typed play is generally established between the ages of 4 to 9 years. During this age, girls take domestic and realistic roles, meanwhile, boys lean more towards fantastical and physically active roles. The degree to which these roles are expressed has been linked to the attitudes of the parents. Children of parents who encourage sex roles and disapprove cross-sex references show more instances of sex-typed play. Although the parents' attitudes are the most influential, other adult role models such as teachers and family members can also reinforce gender play.