I found this article in Scientific American via tweet from Stand to Reason.

Excerpt:

In a series of studies beginning in 1999, he found that when girls had a warm relationship with their fathers and spent a lot of time with them in the first five to seven years of their lives, they had a reduced risk of early puberty, early initiation of sex and teen pregnancy. As Ellis continued this work, however, he became increasingly frustrated. Clearly, the association between fathers and daughters was profound. Yet he could not determine whether the parental behavior caused the consequences he was seeing in the daughters. An alternative was that girls who begin puberty early and engage in risky sexual behavior do so because they inherited certain genes from their parents. Fathers might pass on genes linked to infidelity to their daughters, in whom they could be associated with risky sexual behavior and early puberty. Or something else in the family’s environment could be responsible for the changes in their daughters.

Ellis came up with an innovative way to pose the question. He considered families in which divorced parents had two daughters separated by at least five years in age. When the parents divorced, the older sister would have had five more years with a father’s consistent presence than the younger sister. If father absence causes early puberty and risky behavior, then the younger daughter should show more of that behavior than her older sibling. Also, genes or the family’s environment would not confuse the results, because those would be the same for both daughters. It was close to a naturally occurring experiment, Ellis realized.

Ellis recruited families with two daughters. Some were families in which the parents divorced; others were intact, to be used as a control group. He wanted to answer two questions: Was the age at which girls had their first menstrual period affected by the length of time they spent with a father in the house? And did that age vary depending on how their fathers behaved? The second question was added because fathers with a history of violence, depression, drug abuse or incarceration can affect children’s development.

Ellis’s suspicions were confirmed. Younger sisters in divorced families had their first periods an average of 11 months earlier than their older sisters—but only in homes in which the men behaved badly as fathers. “We were surprised to get as big an effect as we did,” Ellis told me. The conclusion was that growing up with emotionally or physically distant fathers in early to middle childhood could be “a key life transition” that alters sexual development.

The next step Ellis took was to look at whether these circumstances could affect the involvement of girls in risky sexual behavior. This time he turned to Craigslist, a classified advertising Web site, and posted announcements in several cities that began, “SISTERS WANTED!” The criteria were very specific: he was looking for families with two sisters at least four years apart in age and currently between the ages of 18 and 36. He limited his search to families in which the birth parents separated or divorced when the younger sister was younger than 14 years. Ellis and his colleagues were able to recruit 101 pairs of sisters, some from families in which the parents had divorced and, using a different ad, some whose parents had not.

This time the researchers found that risky sexual behavior was not related to how long daughters lived with their fathers but to what the fathers did in the time they spent with their daughters. “Girls who grew up with a high-quality father—who spent more time as a high-investing father—showed the lowest level of risky sexual behavior,” Ellis said. “Their younger sisters, who had less time with him, tended to show the highest level of risky sexual behavior.”