How are hereditary disease passed from one another?

genetic diseases are passed through by generaions because the parents of a child may have x or Y(lets juse say Y is a genetic deisease) in their genes. Y would be the dominant trait so it would make the child have that disease. Sometimes the parents don't have the disease but they can still pass it to their children if they have the genes for it. So really it's because of how our ressesive and dominant traits work.

Tori age 12 Surry Maine