Michael Bailey and colleagues have conducted a series of studies looking at the relationship between gender nonconforming behavior and sexual orientation. By gender nonconforming behavior, Bailey means interests, activities, toys, and even body movements that are associated with the opposite sex (e.g., girls who play football, boys who play with dolls). A number of studies show that gay and bisexual men and women recall a higher degree of gender nonconforming behavior than do their heterosexual counterparts. However, these retrospective studies may be biased by selective recall. Prospective studies are really needed. In that vein, a study of childhood home videos supported a relationship between gender nonconforming behavior in childhood and homosexual tendencies in adulthood. It is important to note, however, that there was a lot of variation among these subjects and not all children with gender nonconforming behavior grew up to be homosexual and not all adults with homosexual tendencies showed gender nonconforming behavior in childhood.