Women more likely to go both ways.

• Position: Your Life

Romantic opportunities appear to influence women's sexual identities but not men's, suggests a study by Elizabeth McClintock, assistant professor of sociology at the University of Notre Dame, South Bend, Ind. 'This indicates that women's sexuality may be more flexible and adaptive than men's," says McClintock, whose study relies on data from the National Longitudinal Study of Adolescent to Adult Health, and considers its first (1994-95), third (2001-02), and fourth (2007-08) waves. More specifically, she tracked 5,018 women and 4,191 men as they moved from adolescence to young adulthood. On average, they were 16 years old in Wave I, 22 in Wave III, and 28 in Wave IV.

Confirming previous research, McClintock found that women were more likely than men to report bisexuality, while men were more likely to report being either "100% heterosexual" or "100% homosexual." She also found that women were three times more likely than men to change their sexual identities from Wave III to Wave IV. Individuals were not asked about their sexual identities until Wave III--the choices being 100% heterosexual, mostly heterosexual, bisexual, mostly homosexual, and 100% homosexual.

In each wave, participants also were asked if they ever had experienced same-sex attraction or participated in same-sex sexual activity. 'Women have a greater probability than men of being attracted to both men and women, which gives them greater flexibility in partner choice. Having flexible sexual attractions may grant greater importance to contextual and experiential factors when it comes to sexual identity."

McClintock's research showed that women with more education and who were physically more attractive (as rated by their interviewers) had higher probabilities of identifying as "100% heterosexual" than other women in Waves III and IV.

In addition, women who had a child by Wave III were less likely than other women to identify as "100% heterosexual" in Wave IV. McClintock speculates that women who avoid young motherhood, are physically attractive, or have high levels of education may be less likely to explore relationships with same-sex partners because...