I know for sure that my dad, sister, and cousin (on my dad's side) all had depression. My dad is still being treated for it, has been taking antidepressants for 10+ years. Idk about my sis and cousin. I'm also pretty sure my sister has anxiety, and I have the same suspicion for someone I know is a relative (again on my dad's side) but I'm not sure how exactly I'm related to her, lol.
Everyone in my family is pretty closed off about these kinds of things, so it wouldn't surprise me to find out if more of my family members struggle or had struggled with mental illness and I just don't know about it. My immediate family lives 20+ hours away from the entire rest of our family, so I don't see how they function day-to-day. Everyone puts on their best show for Christmas!