The number of surveys and transitions that each of the participants contributed to the analyses are shown in .Combining reports across the four waves, 10% of males and 20% of females at some point described themselves as mostly heterosexual, bisexual, mostly homosexual, or completely homosexual, while 2% of both males and females reported ever being “unsure” of their orientation. Cross-sectional distributions (including reports from four waves of data collection) of sexual orientation identity by age are shown in . It can be seen that the proportion of participants describing themselves in each of the sexual orientation identity subgroups varied widely by age and gender. For instance, over the 10-year period from age 13 to 23 years, among males, the proportion describing themselves as mostly heterosexual rose from 2.4 to 5.9%, as bisexual from 0.4 to 0.6%, and as mostly or completely homosexual from 0.3 to 3.5%. Over the same 10-year age period among females, the proportion describing themselves as mostly heterosexual rose from 4.0 to 12.3%, as bisexual from 0.6 to 2.1%, and as mostly or completely homosexual from 0 to 1.0%. In comparison, the proportion describing themselves as completely heterosexual or “unsure” of their orientation decreased with age in both males and females.
Participants in the Growing Up Today Study reporting sexual orientation identity across multiple waves of data collection (1999–2005) from ages 12 to 23 years
Population proportions for each sexual orientation identity minority group, by age
Results of generalized estimating equation models using repeated measures to examine observed gender and age patterns in each sexual orientation identity category indicated that, after adjusting for age, gender predicted all sexual orientation identity subgroups, as shown in (p<05). Male gender was positively associated with identifying as completely heterosexual, mostly homosexual, and completely homosexual, while female gender was positively associated with identifying as mostly heterosexual, bisexual, and “unsure.” After adjusting for gender, older age was positively associated with all sexual minority groups (p<05 for all models). Identifying as completely heterosexual or “unsure” decreased significantly with age, while identifying with any of the sexual orientation identity minority categories increased significantly with age. No age by gender interactions were detected.
Multivariable odds of self-reported sexual orientation identity category associated with gender and agea
Transition matrices (with their corresponding mobility scores with standard errors below their respective transition matrix) are shown in for males and for females. For example, in , by examining the first column and second row of the transition matrix of younger males, it can be seen that 55.1% of the transitions that occurred among 12–17 year old males who reported a sexual orientation identity of mostly heterosexual changed their report to completely heterosexual at the next report. The mobility score (M = 0.081) for this transition matrix indicated that, of all of the transitions (that is, all the occurrences of two consecutive waves of data) that occurred among males who were 12–17 years old, 8.1% of transitions resulted in a change in reported sexual orientation identity. In analyses stratified by gender, mobility scores did not differ by age group (males p = .27; females p = .22), indicating that the amount of mobility in sexual orientation identity (that is, the likelihood of changes in reported sexual orientation identity) did not differ significantly for youth ages 12–17 years compared to those ages 18–21 years. However, there was a significant difference in mobility scores by gender, with females having a higher mobility than males in the younger group (p<0001) and older group (p = .0002) (see , ).
Sexual orientation identity transition matrices and mobility scores for male adolescents, by age group
Sexual orientation identity transition matrices and mobility scores for female adolescents, by age group
Mobility scores with their standard errors at each integer age in years for males and females are shown in , , , and . Inspection of these figures supports five key observations: (1) Mobility scores were relatively low (approximately 0.1) when the consistently completely heterosexual group was included in the sample (, ), because this group, by definition, had zero mobility and they made up the vast majority (78.5%) of the sample of transitions. (2) When the consistently completely heterosexual group was included in the sample, with or without the “unsure” group, females reported higher mobility than males (, ). Consistently completely heterosexuals made up a larger proportion of transitions among males than among females (84.0% vs. 75.2% of transitions). (3) While mobility scores appeared to peak at the youngest ages (see especially ), when the “unsure” group was excluded (see ), this peak appeared attenuated and scores were stable throughout most of the observed age period. As mentioned previously, however, tests of age differences in mobility were not statistically significant. (4) When consistently completely heterosexuals were excluded from the sample (, ), as expected, mobility scores increased substantially (ranging from approximately 0.5 to 0.8). (5) Again, when consistently completely heterosexuals were excluded, the previously observed gender difference in mobility scores was eliminated, with gender-specific score lines even crossing at several points, indicating that sexual orientation identity mobility did not vary by gender among those who self-reported a minority sexual orientation identity at some point in the observation period.
Sexual orientation identity mobility scores and standard error bars in the full sample of adolescents
Sexual orientation identity mobility scores and standard error bars in a subsample of adolescents, excluding the “unsure” group
Sexual orientation identity mobility scores and standard error bars in a subsample of adolescents, excluding the consistently completely heterosexual group
Sexual orientation identity mobility scores and standard error bars in a subsample of adolescents, excluding both the “unsure” and consistently completely heterosexual groups
In subanalyses to characterize trajectories in sexual orientation identity reported by individuals over three or more waves, we observed 80 distinct patterns among older boys, 89 among younger boys, 140 among older girls, and 119 among younger girls. As there were six possible sexual orientation reports, there are 64=1296 possible distinct patterns among those who reported their sexual orientation identity for all four waves. The patterns of sexual orientation identity trajectories are detailed in . The vast majority of the participants consistently categorized themselves as completely heterosexual.
Sexual orientation identity trajectories of adolescents, by age groupa and gender (N=9536)a
Four chi-square tests were used to assess associations among the five main categories (immobile, mobile toward completely heterosexual, mobile toward LGB, multidirectional, and ever “unsure”) in younger males and older males, younger females and older females, older males and older females, and younger males and younger females. All four tests resulted in 4 degree of freedom chi-square test statistics of 36.7, 47.2, 70.2, and 72.9, respectively, all with p<.001, indicating that there were significant age and gender differences in the distribution of sexual orientation identity trajectories. Tests were also conducted to compare the proportion of immobile participants in each subpopulation. Again, four chi-square tests were conducted between younger males and older males, younger females and older females, older males and older females, and younger males and younger females. We found in these analyses that male gender and older age were associated with greater immobility (1 degree of freedom chi-square test statistics of 10.6, 39.9, 68.4, and 4.0 all ps<.05). Similarly, we conducted four chi-square tests to compare the proportions of ever “unsure” and found that there were no gender differences (1 degree of freedom chi-square test statistic of 0.3, when comparing younger males to younger females, and 1 degree of freedom chi-square test statistic of 1.0, when comparing older males to older females); however, there were significant age differences for ever reporting “unsure,” where those in the younger groups were more likely to ever report “unsure” than those in the older groups (1 degree of freedom chi-square test statistic of 39.7, for younger males vs. older males, p<.01 and 1 degree of freedom chi-square test statistic of 65.8 for younger females vs. older females, p<.01).
Of those who reported their sexual orientation identity at least three times, 238 participants reported “unsure” at least once, including 16 who reported “unsure” more than once, with 80% of those reporting “unsure” at their first sexual orientation identity report. Four percent of the younger boys, 1% of older boys, 4% of younger girls, and 1% of older girls who had reported sexual orientation identity at least three times ever reported “unsure.” Among those who ever described themselves as “unsure” of their orientation identity, 34% at some point described themselves as sexual minority (that is, mostly heterosexual or LGB), whereas, among those who never reported “unsure,” only 18% described themselves as sexual minority; this difference was statistically significant (p<.001).