Diseases in gift

I do believe. Some of the diseases are hereditary. To pass the diseases through generation, their is an hereditary pattern that called Mendel's Law of Inheritance. But the case of one gene one disease is always valid. There is some gene that cause by one gene but some is because of multiple gene. But there is some cases that both heredity and environment. For example, the pregnant woman is drinking and smoking. Her child have a great possibility of genetic abnormality. So I his child have an offspring, he will pass that abnormality.

Yes some disease are hereditary like brain disorders..