Green sea turles are fascinating, lovely creatures. They are one of a number of species in which gender is not determined by chromosomes.
“…the northern GBR green turtle rookeries have been producing primarily females for more than two decades and that the complete feminization of this population is possible in the near future.”
Current Biology: http://www.cell.com/current-biology/fulltext/S0960-9822(17)31539-7
It seems that their adult population is now 87% female. How/why? Because sea turtles gender is determined by the temperature of the sands in which eggs and laid, mature and hatch.