Genetic mutations most common in body parts that are used frequentlyare mainly caused by diseases associated with fetaldevelopmentcan occur naturallyare always passed on to the next generation

Genetic mutations can occur in one gene (monogenic disorder), and by mutations in multiple genes (multifactorial inheritance disorder).  Also mutations can occur through some factors as a combination of gene mutations and environmental factors, or by damage to chromosomes (changes in the number or structure of entire chromosomes, the structures that carry genes). These can be carried from generation to generation.

this is a good question! i'll do some research and come back when i have the answer!