Inheritance is a prime antecedent of many neurodegenerative disorders. Primarily these disorders result from a genetic mutation or imbalance, passed from parent to child.
With autosomal dominance disease, a parent with the trait will pass on that mutation to half there offspring with an equal split between male and female sibs. The disease type for example Huntington’s is most characterised as vertical transmitted appearing with each generation.
With autosomal recessive diseases, for example Cystic Fibrosis, both parents while clinically asymptomatic, must pass in combination, the mutation on to 25 % of the offspring. This is called horizontal transmission.
In polygenic diseases there is an interaction between genetic and non genetic factors in what can be complex ways e.g. diabetes, heart disease and cancer.