Does anyone know what determines whether a ball python develops into male or female? Is it envirnomental determination? Or is it a genetic mechanism such as our XY system?

I know for many reptiles sex choice is usually determined by the temperature at which early embryonic development takes place. However, if that was the case couldn't breeders try to control whether or not they have males or females? And since females are ususally worth more money.......

I havent seen any sex-linked traits being discussed in these parts.....of course this doesnt mean they dont exist..........

Could it be the ratio of different types of sex chromosomes?