African-American activists aggressively called out arguments about genetic and biological differences as legacies of racist, Nazi science. By contrast, the marriage-equality movement has embraced biological determinism. Gay and lesbian activists have led the way popularising the idea that identity is biologically determined
In evangelical blog contexts there's an idea that has not been discussed as much as it probably could, which is that when straight American evangelicals get married based on a kind of heteronormative biological determinism we may be looking at a culture in which, to borrow an old Catholic theological idea, concupiscence has gone from a reason to refrain from marriage to the most celebrated reason for straights to be married. What was once potentially construed as an emotional/physical state to be found permissible within marriage, the sparks are expected to be there as a precondition of marriage. Or, maybe we can let a commenter at Mere Orthodoxy spell it out.