Developing Sea Turtle hatchlings do not have sex chromosomes so their gender is determined by the temperature within the nest.
The eggs are affected by the temperature at which they are incubated during the middle one-third of embryonic development, the so called “thermosensitive period” (TSP).
There is a “pivotal” temperature which varies slightly among species, ranging between approximately 28-29 °C (83-85 °F), at which embryos within a nest develop into mixed males or females and more rarely intersex individuals.
Temperatures above this range produce females and colder temperatures produce males.