Can my cousin get diabetes?

so i just went camping with my aunt, uncle, and 2 cousins. my younger cousin "hannah" is 4 and i noticed shes always thirsty and all she wants is chocolate milk and kool-aid and the only food she will eat is hot dogs, mashed potatoes and pop tarts... and sweet stuff! i have diabetes and it runs in the family so does that mean shes gonna get it to and if she eats nothing but junk and like no water or anything healthy does that make her at higher risk for diabetes? i was just curious i don't want to say anything to anyone and not know what im talking about ya know... thank you :) (btw she drinks like 5 cups of chocolate milk a day and some kool-aid)