Why it matters if there's mental illness in your family
If you're going to go to therapy, you have to be prepared to have this person get all up in your business. It's uncomfortable for most, but generally people understand why it's necessary. How can this person help me if I don't actually tell them who I am and what I'm struggling with?
One area that is less understandable for some people, is why the therapist is asking a ton of questions about your family. And not just your parents or siblings, but your grandparents, aunts, uncles, cousins. It starts to feel really intrusive! But we, as your clinician, are not just being nosy. Knowing about mental illness in your family is important for understanding your own context. You do not exist in a vacuum!
So, I'll start with this. There's a concept called The Stress-Diathesis Model of mental illness, and what it says is that mental illnesses/psychological disorders come into being when two things are present: a genetic predisposition and a stressful environment. The genetic predisposition can be about inherited genes, but can also be related to abnormalities of the brain (physical/structural damage or problems with neurotransmitters), and a stressful environment in the womb that impacts/changes the nervous system of the baby.