31 year old female looking to do gender affirming hormone therapy, testosterone. have a family medical history with idiopathic intracranial hypertension. mother has it. great grandmother had it. would taking testosterone cause me to get the disease?

Testosterone does not cause any disease. You should discuss this history with the endocrinologist who will treat you

Some cases of Pseudotumor Cerebri (benign increased intracranial hypertension) have been associated with female menstrual irregularities with hormonal imbalance. Although testosterone has not been implicated, it is important to have close supervision with an endocrinologist, as you proceed. Would be helpful to uncover causation in your relatives.