gender based on temperature

Today I was talking to a friend and discussing what type of topics I could possibly write about. Some of her topics were pretty funny and random like eskimos and zoo animals. However, she mentioned that there are turtles that have their gender based on temperature; I was interested and wanted to find out more. The Painted Turtle is slow moving and likes to be by the water. They like to live by the water and they have a beautiful design in the shell (hence the name "painted" turtle). During the winter, turtles bury themselves in mud to keep themselves warm. The most interesting part about these turtles is that their incubation temperature determines their gender. The low temperatures produces males and high temperatures produces females. I thought the gender fact was particularly interesting and now I feel like a talk host for the animal planet. I wasn't even aware that any animal can have their gender based on an outside source (i.e. environment). I originally thought that gender is already "predetermined" and can't be affected based on the environment. I found this to be quite interesting and I hope there are people who also learned something new about turtles.

What if human beings were determined by outside environmental effects? Would we have a country dominated by males and then another country dominated by females? This of course would never happen because humans aren't close to the reptilia class. But what would our world be if our world determined people's gender based on temperature.