Pregnancy?

So I'm 19, and I've already decided that if and when I had kids, i would want to have them through adoption. I told my mom and my therapist (I have pretty bad anxiety) and they both said I was too young to make that decision. The thing is, my family is very predisposed to all types of cancer (ovarian, breast, colon, lung). That's scary enough for me to deal with, and I wouldn't want a child to have to deal with these bad genetics as well. What do you think? Am I too young to have decided this?