What’s an actual way to prove that some disease/illness is genetics?

Question

I just don’t get why we blanket everything under genetics.. Can that actually be proven? For instance with depression, I often hear yeah it’s genetics, nothing to be done but medication. But if a parent raises a child while battling depression, how on earth would they be able to show up fully to be able to raise a healthy, emotionally supported child? If we know adverse childhood experiences and emotional neglect changes the brain, then how is it supposed to make the right amount of chemicals? So when it’s said depression is genetics, how did they actually prove that for instance?

In: 1

Answer 1

Ideally you could study identical twins separated at birth. Or failing that you could count how many pairs of identical twins shared a diagnosis compared to how many pairs of non identical twins.