The film offers various scientific evidence, witty arguments, and compelling stories working to undermine the idea that homosexuality is a choice, but in doing so also offers some troubling assumptions about gender and its supposed links to sexuality. A short cartoon in the style of a public service announcement captures this duality very well.
The narrator offers various arguments against homosexuality as a choice - those parts based on scientific study (which therefore supposedly carry more legitimacy). Apparently, several recent studies have suggested that having older brothers significantly increases the odds of the youngest broth being homosexual. This is - supposedly - because the mother's body reads a male fetus as a foreign object and produces antibodies against it. The more male children the mother has, the "more adept her body becomes at feminizing the fetus, which may explain why with every successive boy, the odds that he will be gay go up significantly."
(I would have just guessed statistics... the more kids you have that aren't, the higher chance your next one will be. But what do I know? And what does "feminizing the fetus" even mean? Pink chromosomes?)
This otherwise potentially informative cartoon actually reinforces widely-held myths about gender and sexuality, most notably that femininity is biological and, when coupled with the male sex, implies homosexuality. To present the argument that homosexuality is a genetic matter implies only genetic causality, which may or may not include room for other theories like constructivism. However, to argue that homosexuality is a genetic matter because the male fetus is "feminized" and therefore increasingly likely to be gay implies that it is in fact the biological assignment of femininity to males that causes homosexuality, not some genetic combination that occurs randomly in roughly ten percent of the population.
The concept of biological femininity only reinforces the commonly held belief in the synonymy of gender and sex, implicitly guiding viewers to the idea that gender is something essential, inheritable, and genetic. It disallows for the possibility of societal influence and construction of gender roles, performance, and identity.
In other words, it's one thing to say that being gay is genetic. It's an entirely different thing to say that being gay (in the case of men, anyway) is because of feminization. Doing so only falsely links sexuality to gender.