“Sexual orientation, specifically being gay, is primarily a result of psychological factors or social influence rather than innate biological factors, and it can be changed.”

The data summarised in the present review suggest that both gender identity and sexual orientation are significantly influenced by events occurring during the early developmental period when the brain is differentiating under the influence of gonadal steroid hormones, genes and maternal factors.

There is strong evidence that sexual orientation is largely tied to biology and that initial gender assignment is the strongest predictor of gender identity in the case of intersex children.

The research on SOCE published since APA's (2009) task force report and resolution has continued to support the conclusions that former participants in SOCE look back on those experiences as harmful to them and that there is no evidence of sexual orientation change. The consensus panel that APA conducted for SAMHSA likewise found no credible evidence to support SOCE with children and adolescents and called for an end to SOCE (SAMHSA, 2015).

Experts at the U.S. Substance Abuse and Mental Health Services Administration (SAMHSA) have concluded that sexual orientation or gender identity change efforts are “coercive, can be harmful, and should not be part of behavioral health treatment” (SAMHSA, 2015). Efforts to change an individual's sexual orientation or gender identity may encourage people to hide these aspects of their identity, which can lead to mental health problems such as depression, sexual problems, low self-esteem, and suicide.

This assessment looked at the nature, quality and quantity of evidence on conversion therapy to change sexual orientation and gender identity exclusively. It found that the evidence base for conversion therapy for sexual orientation is long-established, extending over 20 years, while for gender identity the evidence base is newer. Despite being fewer in number, studies looking at conversion therapy for gender identity were assessed as being stronger in design than those for sexual orientation.

Results: Among adults older than 18 years, 4.1% reported a change in sexual orientation and 3.6% reported a change in gender identity. Among ...

There is no consensus among scientists about the exact reasons that an individual develops a heterosexual, bisexual, gay, or lesbian orientation. Most people experience little or no sense of choice about their sexual orientation.

This research demonstrates that structural stigma represents an important, but thus far largely underrecognized, mechanism underlying mental health disparities related to sexual orientation among youth. Structural stigma—including state-level policies, public opinion, and density of same-sex couples—affects health outcomes, but does not alter sexual orientation itself.

Sexual identity was relatively consistent for exclusively heterosexual and homosexual boys and girls over time. Some bisexual youths were consistent in their identity over time, but many others changed. The data indicate little congruence between identity and behavior markers of sexual orientation, with associations differing by sex and race/ethnicity, suggesting complex developmental patterns rather than simple social influence.

However, after reviewing the research, we concluded that there is no credible evidence that sexual orientation can be changed through therapeutic intervention. While some beneficial SOCE outcomes (such as acceptance of same-sex attractions and reduction in depression and anxiety) were reported, the overall results support the conclusion that sexual orientation is highly resistant to explicit attempts at change and that SOCE are overwhelmingly reported to be either ineffective or damaging by participants.

Programs designed to change a person's sexual orientation or gender identity are linked to depression, PTSD and suicidality in a Stanford Medicine-led study. Participants who experienced formal efforts to change their sexual orientation reported more symptoms of post-traumatic stress disorder, while those who experienced efforts to change their gender identity exhibited more symptoms of depression, the study found. People who reported experiencing both forms of conversion practices had more symptoms of PTSD and suicidality.

Reported changes in sexual orientation following completed SOCE ranged from increased homosexuality for a few men (6%, N=4), no change for about one in five (22%, N=16), generally stable homosexual attraction for over four in 10 (43%, N=31), and heterosexual transition for about a third (32%, N=23). The finding that some self-reported sexual orientation change did occur is consistent with previous research and with evidence that sexual orientation is not an immutable genetic trait, spontaneously changes for many over the life course.

The best-established facts in relation to homosexuality point to developmental-psychological, not genetic or physiological, causation. In contrast, many studies have shown that the most significant factor which correlates with homosexuality is “gender nonconformity” or same-sex peer isolation. Therapeutically, a holistic approach, simultaneously addressing the emotional, moral, and spiritual components of the psyche, offers the best opportunity for overcoming homosexuality.

Exposure to SOCE was associated with significant declines in same-sex attraction (from 5.7 to 4.1 on the Kinsey scale, p <.000), identification (4.8 to 3.6, p < .000), and sexual activity (2.4 to 1.5 on a 4-point scale of frequency, p < .000). From 45% to 69% of SOCE participants achieved at least partial remission of unwanted same-sex sexuality; full remission was achieved by 14% for sexual attraction and identification, and 26% for sexual behavior.

Among the most notable were a series of studies Pillard and J. Michael Bailey... conducted in the early 1990s that found that homosexuality is largely biologically determined, not environmentally influenced. In their findings, published in the Archives of General Psychiatry, they argued that decades of psychiatric research into social and cultural causes show “small effect size and are causally ambiguous.” It shows it is largely genetic because the experimenters used a control group. The control group, adopted siblings who are gay, had only a 5% correlation – the nurture made little impact.

Several studies have found correlations between same-sex sexual preferences and environmental conditions. In this case the “environment” can be the uterine environment... or the environment can refer to conditions after birth. Somewhat more compelling is the work on the prenatal environment and homosexuality. According to many of these studies, differential exposure to prenatal hormones, specifically testosterone, influences sexuality later in life.

Research from the UK indicates that social class may influence sexual identity formation for young LGB people, with working class young people more likely to ascribe to an LGB label than middle class young people. However, this addresses identity formation and labeling rather than the underlying orientation itself.

By the end of this review, the facts and analysis should support the hypothesis that sexual orientation is the result of a complex combination of one’s genes, environment, and hormones. Also, the facts and analysis should create a clear picture that one’s sexual orientation is not a choice, nor is living a non-heterosexual lifestyle.

The American Psychological Association states that most people experience little or no sense of choice about their sexual orientation. There is no scientific evidence that sexual orientation can be changed through therapeutic intervention, and efforts to do so (often called conversion therapy) are ineffective and can be harmful. Sexual orientation is likely influenced by a complex interplay of genetic, hormonal, developmental, social, and cultural factors, with substantial evidence for biological contributions.

This paper reports results from four large data sets reflecting longitudinal analysis of the same individuals over time in population-based samples (three from the United States and one from New Zealand). All demonstrate that significant change in each of the elements of sexual orientation is possible. The percentage changing from homosexuality to heterosexuality ranged from 13% to 53%, while the percentage changing from heterosexuality to homosexuality ranged only from 1% to 12%.