​Alzheimer’s disease has been linked with genetics. As per MayoClinic, the most common gene associated with late-onset Alzheimer’s disease is apolipoprotein E (APOE). “One copy of the APOE gene comes from the mother and another from the father. Having at least one APOE e4 gene doubles or triples the risk of getting Alzheimer’s disease. Some people have two APOE e4 genes, one from each parent. Having two genes increases the risk of getting Alzheimer’s disease even more, about eight- to twelvefold,” it explains.​