My mother has a bad temper, my mother's mother a worse temper, how much is genes and how much is environment?

Can't be sure, and..: What parts of the temper issues of your mother and grandmother are inherited and what parts from environment are impossible to know for sure, but chances are good that some of both potential causes are present. In my experience, a serotonin-enhancing medicine and Neurontin (gabapentin) can often be very helpful as also may be Abilify (aripiprazole) in a low dose (2-5mg each am). All alcohol and illicit drug use should be stopped.