A DNA sex is a set that can merge successfully with another set that produces an offspring. This is not always possible in all life because some sections of th

A DNA sex is a set that can merge successfully with another set that produces an offspring. This is not always possible in all life because some sections of the DNA are incompatible when swapped. Here is the sparrow with four sexes: https://www.nature.com/news/the-sparrow-with-four-sexes-1.21018 https://www.nature.com/news/the-sparrow-with-four-sexes-1.21... Conversely, what we think of sex (the genitalia and dimorphism identification) may not even be defined specifically by genes sets, but by epigenetic/environmental responses. Even though alligators have DNA sets that are swapped, they are largely physically sexed by temperature: https://en.wikipedia.org/wiki/Temperature-dependent_sex_determination https://en.wikipedia.org/wiki/Temperature-dependent_sex_dete... It even has an advantage, as females without mates can sometimes spontaneously reproduce and have offspring that are both male and female: https://en.wikipedia.org/wiki/Parthenogenesis_in_squamata https://en.wikipedia.org/wiki/Parthenogenesis_in_squamata