A reader writes:
The National Geographic clip on twins was fascinating, not least for the language it used. At eight weeks, the clip says, the brain of a fetus with a Y chromosome is bathed in testosterone. "Not enough, " it hypothesizes, and the brain isn't sexualized to be attracted to women. The clip doesn't say if a fetus without the Y would receives 'too much' testosterone or 'not enough' estrogen at eight weeks to develop a same-sex attraction.
Later, the clip speaks of switches in the brain causing disease, and it flashes back to the gay twins as it emphasizes the word 'disease,' visually implying the gay twin is diseased, the straight twin isn't, because of the way the switches in their genes were activated. In both instances, the underlying tone is a tone of "being gay is wrong, a genetic disease." This tone, it feels to me, forgoes any question of potential gain for same-sex attraction, re-enforcing negative social bias.
I also thought it amazing that the research suggests attraction to men is the norm, attraction to women must be activated with a testosterone bath. I would have assumed the opposite, that attraction to men must be activated. (I am a heterosexual woman.)
Describing natural phenomena that are not of the norm, without describing them as somehow defective or diseased, is difficult given our cultural inheritance. I don't think all of it can be called bigotry as such; most of it is simply driven by majoritarian default assumptions. Freud saw homosexuality as not normal. But he didn't draw any "disease" assumption from that and saw heterosexuality as equally worthy of explanation.