Nelson Morales took a photography workshop that changed nearly everything.

He had been working since 2012 on a project about the muxes, a group of people in Mexico who are born male but adopt norms and customs associated with women (and who sometimes are considered a third gender).

The muxe community is concentrated in the isthmus of Tehuantepec, in southern Mexico, and is a favorite subject for foreign artists and journalists. “Many artists come to Juchitán,” a town on the isthmus, Mr. Morales said. “But they always do the same reports, the same point of view from outside.” Though Mr. Morales was born in the Tehuantepec region, he admits that his original pictures looked much like everyone else’s — pretty, but uninteresting.

But in 2015, Mr. Morales took a workshop with Antoine d’Agata, a Magnum photographer, that pushed him to get to the heart of himself and his practice.