How old do you have to be to get dry eyes?

last week I had a swollen cornea in my right eye, I wear contact lenses and the Doctor kept asking if I slept with them in, but I haven't. He gave me some eye drops to put in, and I've been using lubricating drops as well. the eyes feel better now, and I've only been wearing glasses, but my eyes feels itchy, and I add some of the lubricating eye drops in and it feels better. The eye drops are from my mom who has dry eyes, and I was wondering how old you have to be to have them? I'm 20 but I live in AZ and it's been a dry windy summer. My mom has dry eyes and got them when she was fairly young (about 35) could it be hereditary?