A new research has shown that girls in homes without a biological father are more likely to hit puberty at an earlier age.
According to the new study led by researchers at the University of California, Berkeley's School of Public Health, the absence of a biologically related father in the home predicted earlier breast and pubic hair development, but only for girls in higher income households. The findings held even after the girls' weight was taken into account.
In this new study, researchers recruited 444 girls ages 6-8 through Kaiser Permanente Northern California, and have been following them annually. Their analysis was based on the first two years of follow-up. They considered signs of puberty that occur before the start of menarche. In interviews with the girls' caregivers, the researchers asked about the residents in the girls' homes and their relationships to the children.
Among the girls studied, 80 reported biological father absence at the time of recruitment. Contrary to what the researchers expected, the absence of a biologically related father was linked to earlier breast development for girls in higher income families - those having annual household incomes of 50,000 dollars or more. Father absence predicted earlier onset of pubic hair development only in higher income African Americans families.
Another theory that has been posited is that girls without a biological father in the home are exposed more to unrelated adult males - specifically, the pheromones of these males - that lead to earlier onset of puberty. However, in this study, the presence of other adult males, including stepfathers, in the home did not alter the findings.
Another possibility is that higher income girls in father-absent homes may be exposed to more artificial light - which has been shown to accelerate puberty in animal studies - through television, computers and other forms of technology, according to the study authors. The researchers also suggested that higher income African American girls may be more exposed to certain beauty products, such as hair straighteners, which have estrogenic properties that could influence pubertal timing.
The findings will be published in the Journal of Adolescent Health.