Childhood Sexual Abuse Does Not Cause Homosexuality
Is there any truth to the claims that sexual abuse can lead to homosexuality?
Obviously there is not a causal relationship between childhood sexual abuse and homosexuality. If childhood sexual abused caused homosexuality then we could safely conclude that anyone who was sexually abused as a child would be homosexual. Such a statement can be disproved by finding a single person who was sexually abused as a child and who is not a homosexual. I am confident that somewhere in the seven or so billion people that populate this earth there exists at least one person who was sexually abused as a child yet identifies as a heterosexual. Ergo, sexual childhood abuse does not cause homosexuality.
Granted, the quotations you cited did not claim that childhood sexual abuse leads to homosexuality. Rather, they note that there is a strong link between the two. So let's talk about whether there exists a correlation between childhood sexual abuse and homosexuality.
The Correlation Between Childhood Sexual Abuse and Homosexuality
Whether there is a higher incidence of childhood sexual abuse among homosexuals than heterosexuals depends on which studies you read. For instance, in The prevalence of child sexual abuse: Integrative review adjustment for potential response and measurement biases, authors Kevin Gorey and Donald Leslie note:
Female and male child sexual abuse prevalence estimates adjusted for response rates ... and adjusted for operational definitions ... were 14.5% and 7.2%.
In the study History of Childhood Sexual Abuse and HIV Risk Behaviors in Homosexual and Bisexual Men, David Brennan et al find that "childhood sexual abuse was reported by 15.5% of the survey respondents." (Their survey was given to men, 99.5% of which identified as gay or bisexual.)
If we take these numbers at face value then we are led to the conclusion that the incidence of childhood sexual abuse in homosexuals and bisexuals is nearly twice of that of the general population.
The History of Childhood Sexual Abuse and HIV Risk Behaviors in Homosexual and Bisexual Men study notes that victims of childhood sexual abuse are much more likely to engage in risky behaviors, including HIV status, STDs, drug use, and prostitution. And Wikipedia has a rather detailed look at the psychological and physiological harms caused by such abuse:
Psychological, emotional, physical, and social effects include depression, post-traumatic stress disorder, anxiety, eating disorders, poor self-esteem, dissociative and anxiety disorders; general psychological distress and disorders such as somatization, neurosis, chronic pain, sexualized behavior, school/learning problems; and behavior problems including substance abuse, self-destructive behavior, animal cruelty, crime in adulthood and suicide.
If we agree that there exists a higher incidence of childhood sexual abuse among homosexuals that implies a positive correlation, but one is left wondering whether the correlation can be described by other factors.
Men vs. Women
If there is a strong correlation between childhood sexual abuse and homosexuality and if factors such as the genders of the abuser and abused are irrelevant then we would expect to see a higher percentage of lesbians than gay males in society, given the fact that women are nearly twice as likely to be the victims of sexual abuse than men. Yet according to The prevalence of homosexual behavior and attraction in the United States, the United Kingdom and France:
Examination of homosexual behavior separately finds that 6.2 ... and 3.6 ... of females in the United States ... report having had sexual contact with someone of the same sex in the previous 5 years.
Yet twice as many women suffer from childhood sexual abuse yet only half as many have homosexual experiences.
This would lead one to conclude that the correlation lies more between same-sex abuse and homosexuality. Presumably, most sexual abuse perpetrators are men, so girls are suffering from heterosexual abuse while boys are suffering from homosexual abuse.