Most types of dementia are not genetically inherited from parents. Huntington's disease is one kind of dementia that is inheritable and passed on to a child from either parent with a dominant gene for the disease.
Alzheimer's disease, the most common form of dementia, is not inherited in the vast majority of cases. Early onset Alzheimer's is extremely rare, accounting for fewer than one in 1,000 cases. It is more inheritable than late onset of the disease. Approximately one-third of those with fronto-temporal dementia, a less common form, have the disease in their family history. Environment and lifestyle play a large role in the development of dementia. Regular exercise, maintaining a healthy diet, social activity and mental activity can help reduce the risk of developing dementia.