>No scientific studies have performed fecal microbiota transplants (FMT, or "poop transplants") from straight men to gay men (or the reverse) specifically to test effects on sexual orientation or attraction.
>Why this specific experiment hasn't (and likely won't) happen:Ethical barriers: Testing whether changing gut bacteria alters core sexual orientation would be highly controversial, potentially harmful, and difficult to justify ethically. Sexual orientation isn't a disease or medical condition to "treat" with experimental procedures.
>Practical issues: FMT is mainly used for serious conditions like recurrent C. difficile infections. Using it experimentally for behavioral traits raises major safety and consent concerns.