I'm a daddy, leopard geckos just hatched!! (DUW!!)

This is something completely new to me. Different temperature can result in different sex for the hatchlings. Do you know the science behind it?
What do you use to keep the temperature at that high for your Leopard geckos' eggs? If you are getting eggs so frequently, are you able to sell some of the offspring to the pet stores or directly to other reptile owners?

Good to have you here. We learn something new every day.