Where does the conclusion that those who are/were third gender are ‘men who fail to live up to […] masculine gender stereotypes’ come from?
Re Hijra as an example of the concept of a ‘third gender’ comes from:
"When Hijra grew up, they understood that they were different from
other males in numerous respects, such as that they used to play with girls and have feelings for boys….Even though India is accepting of a wide range of cultures, a family in that situation cannot tolerate it when their male child begins to act in a feminine manner. It is usual for parents to explain their child's reaction to many situations (Chakrapani, 2010). Furthermore, the hijra is finally banished from their families due to their cross-dressing. Their female attitudes become impediments to their academic and professional success. They are routinely abused, forced, and exploited outside of their families and social lives (Chowdhury, 2020). In many cases, social marginalization begins at home."
Hossain et al 2024
Other interpretations are, of course, possible but that reads to me that young effeminate (hate that word), likely gay, boys/young men are rejected by both family and wider society for being gay and as a result this subculture was created. To ‘other’ gay men as not being really or fully male.