Nearly one in 10 sexually experienced teenagers in New York City have had a same-sex partner, and of these, two-thirds also have had partners of the opposite sex, according to an analysis of two cross-sectional surveys of more than 17,000 public high school students.¹ Sexually experienced teenagers who have had partners of both genders, as well as females who have had only female partners, are the most likely to report behaviors that increase their risk for STDs, and to have experienced intimate partner violence and forced sex. Meanwhile, nearly 40% of teenagers who have had same-sex or male and female partners consider themselves heterosexual, the analysis shows.

Investigators analyzed combined data from the 2005 and 2007 New York City Youth Risk Behavior Surveys, the largest of 22 local surveys within the national Youth Risk Behavior Surveillance System. Using a two-stage cluster sample design, which produces a representative sample of New York City public high school students, they administered anonymous questionnaires to students in randomly selected classes from schools throughout the city. Students were asked if they had ever had intercourse; their age at first intercourse; the number of partners in their lifetime and the last three months; whether they had used a condom or consumed alcohol or drugs during their most recent intercourse; whether they had ever experienced forced sex; and whether they had experienced intimate partner violence during the last year. They also were asked the gender of their partners and whether they considered themselves "heterosexual (straight),""gay or lesbian,""bisexual" or "not sure" of their sexual orientation. Investigators grouped students according to their partners’ gender. They weighted the data to adjust for school and student nonresponse, and analyzed the frequency of responses, which were essentially the same regardless of adolescents’ race, ethnicity or age. They also conducted t tests to assess significance and found differences between weighted prevalence estimates to be statistically significant at p<.05.

Of 17,220 teenagers (mostly 15–17-year-olds) who completed surveys, 3,805 males and 3,456 females reported having had intercourse and provided the gender of lifetime sexual contacts. Among sexually experienced youths, 9% reported contact with same-sex partners, and 66% of these reported partners of both genders. Females were more than twice as likely as males to have had partners of both genders (9% vs. 4%).

Ninety-one percent of sexually experienced adolescents considered themselves straight, 1% gay or lesbian, and 5% bisexual; 3% were unsure. The highest levels of sexual risk--taking occurred among teenagers who had had only same-sex or both male and female partners, nearly 40% of whom considered themselves straight.

Males who had had partners of both genders were significantly more likely than those with only female or only male partners to have had sex by age 13 (72%, compared with 51% and 40%), to have had five or more lifetime partners (64%, compared with 34% and 36%), to have had two or more partners in the last three months (57%, compared with 25% and 12%), and to have suffered intimate partner violence in the previous year (35%, compared with 13% and 6%). These males were much more likely than those who had had only female partners to have used alcohol or drugs in their last sexual encounter (42% vs. 16%) and to have been forced into sex (32% vs. 7%), but much less likely to have used a condom at last sex (44% vs. 80%).

Females who reported only female partners or partners of both genders were more likely than those with only male partners to have experienced first sex by age 13 (57% and 42%, compared with 22%). Females with partners of both genders were more likely than those with only male partners to have had five or more lifetime partners (37% vs. 14%), to have had two or more partners in the past three months (27% vs. 12%), and to report alcohol or drug use during the last sexual encounter (23% vs. 10%). Of females with partners of both genders, 36% reported intimate partner violence, and 34% reported forced sex—significantly higher prevalences than those found among females with only male partners (15% and 16%) or only female partners (14% and 13%).

One limitation of this analysis that the investigators identify is the exclusion of alternative school students and teenagers not in school, who are known to engage in relatively high levels of risk-taking behaviors. Others are its reliance on self-reports of stigmatized behaviors and its failure to distinguish "sexual intercourse" from "sexual contact." Its strength comes from large sample sizes, which allowed the investigators to answer questions about adolescents’ sexual identities and behaviors in the context of their partners’ gender.

Sexual identity, the researchers conclude, is not a proxy for sexual behavior and should not steer adolescent STD prevention programs. Instead, prevention efforts should be based on the number and gender of teenagers’ sexual partners, teenagers’ sexual behaviors and the related risks they may face.—A. Kott