I used to believe in a direct causal link between father absence and early sexual maturity in girls. The reasoning was that a daughter’s sexual development is accelerated when her biological father is replaced by a strange male (such as a stepfather). At the time, I saw this finding as a way to counter the argument that sociobiology denies human plasticity. It also offered hope that we could remedy a large number of social problems by ensuring father presence. Now I can’t help wondering whether all of this distorted my sense of judgment … and that of others.
One of the best studies on this subject is by Surbey (1990), who used a large sample (1,247 daughters) and measured several possible confounding factors: family size, birth order, weight, height, Quetelet Index, and socio-economic status (SES). On none of these measures did the father-absent daughters (16% of the sample) significantly differ from the father-present daughters. Nonetheless, they matured 4-5 months earlier than those who lived with both parents continuously and 7 months earlier than those who had experienced only an absent mother.
That sounds convincing. Yet how well was SES really controlled? The subjects were apparently university students, so they would have shared the SES of their mothers. But what about the SES of their absent fathers? What do we know about them? Typically nothing. And does SES fully capture all of the factors that distinguish father-absent daughters from father-present ones? Could it be that these two groups differ somewhat in their physiological make-up and, perhaps, in their genetic background?
These doubts led Mendle et al. (2006) to control for genetic background by examining the daughters of twin mothers. It turned out that the daughters did not differ in age of menarche if one mother was still living with the biological father and the other was not. Moreover, when the mother’s age of menarche was controlled among unrelated daughters, age of menarche no longer differed between daughters living with stepfathers and those living with biological fathers.
The presence of a step-uncle was as strongly predictive of early menarche as presence of a stepfather. It does not seem necessary for a child to experience the direct environmental influence of a stepfather to exhibit an accelerated age of menarche—as long as she is genetically related to someone who does have a stepfather. In a pair of twin mothers of which only one raises her children with a stepfather, the offspring of both twins are equally likely to display early age of menarche. It therefore appears that some genetic or shared environmental confound accounts for the earlier association found in female children living with stepfathers.
Mendle et al. (2006) raised another point. The correlation between father-absence and early menarche may be an artefact of population substructure:
The wholly Caucasian population of our Australian sample may explain our failure to replicate the strong father-absence association observed in more ethnically diverse American samples. Given that African American and Latina girls experience menarche on average 6 months prior to Caucasians (Herman-Giddens et al., 1997), it may be that the previously established associations between early menarche and lack of a traditional two-parent family structure are affected by racial differences in family structure. Correlates of early menarche may additionally be complicated by effects of poverty or socioeconomic status. For example, Obeidallah, Brennan, Brooks-Gunn, Kindlon, and Earls (2000) obtained a difference in age of menarche between Caucasian and Latina girls, but this effect disappeared after controlling for socio-economic status.
Why didn’t other studies control for ethnicity? Apparently because the authors felt that SES controls were sufficient. This may be true for Hispanic Americans but it is not for African Americans. Even among Hispanics, there may still be substructure effects. It is known that Hispanic SES correlates with European ancestry, so controlling for SES would bias this population toward individuals who are more genetically similar to European Americans.
All of this makes me wonder about all of the data that supposedly prove the adverse effects of single motherhood. Undoubtedly, there are adverse effects. But there are probably many “pseudo-effects” that would persist even if the biological father could be forced to stay around.
For what it’s worth, I spent part of my pre-adult life in a father-absent family (my father died of a cerebral hemorrhage). Yes, there were adverse effects, poverty in particular. Nonetheless, I think I would have ended up being substantially the same kind of person even if my father had continued to live.
Mendle, J., Turkheimer, E., D’Onofrio, B.M., Lynch, S.K., Emery, R.E., Slutske, W.S., Martin, N.G. (2006). Family structure and age at menarche: a children-of-twins approach. Developmental Psychology, 42, 533-542.
Nettle, D. (2008). Why do some dads get more involved than others? Evidence from a large British cohort. Evolution and Human Behavior, 29, 416-423.
Surbey, M.K. (1990). Family composition, stress, and the timing of human menarche. In T.E. Ziegler & F.B. Bercovitch (eds.) Socioendocrinology of Primate Reproduction, pp. 11-32, New York: Wiley-Liss Inc.