Tina's father-in-law thinks that homosexual activity is a choice people make, not a result of genetics. to dissuade him from this erroneous belief, which research findings might she share?

She can share the research that "researchers have been able to create female fruit flies that, during courtship, act like males".

Two Tohoku researchers found that homosexual conduct in specific gatherings of male fruit flies can be changed by their conditions. In particular, they demonstrated that the sexual inclinations of male fruit flies with a mutant variant of a gene known to influence male sexual conduct can change contingent upon whether the flies are raised in gatherings or alone.