sex-determining

Those species of turtle either lack the typical sex-determining chromosomes entirely, or have sex-determining chromosomes which can be inactivated during development.

There are a number of species - primarily rodents - with unusual sex-determining systems, like species with XX/X0 (i.e.

The facts are that if you have the sex-determining-region Y (SRY) gene (which usually comes on the Y chromosome, but may be missing or defective, or may be on the X chromosome because genes do funny things), you are most likely biologically more-male-than-not and if you don't you probably are more-female-than-not.

While it's always cute when people pretend that human sex is simple and things only get complicated when gender identity is considered, chromosomes aren't genes, the Y chromosome isn't the “testosterone gene”, XY females exist, XY females with a normal copy of sex-determining region Y (SRY) exist, and, as was discovered recently, XY females with a normal copy of SRY who have borne children exist.

While it's always cute when people pretend that human sex is simple and things only get complicated when gender identity is considered, chromosomes aren't genes, the Y chromosome isn't the “testosterone gene”, XY females exist, XY females with a normal copy of sex-determining region Y (SRY) exist, and, as was discovered recently, XY females with a normal copy of SRY who have borne children exist.