Humans are born with 23 pairs of chromosomes and 20,000-25,000 genes. Genes are sequences of nucleotides (the basic structural unit of nucleic acids) that code for the amino acid sequence of proteins. It is important to know that the genetic information contained in the chromosomes does not directly determine what happens to us. Rather, the genes provide information about what can be done. What actually happens is an interaction between the genes and the environment. That is, how we live influences the action of our genes - the context is supreme. Genes are the cause of Alzheimer’s in only 1 percent of cases. A form of the apolipoprotein E gene called e4 increases the risk of getting Alzheimer’s by 2-10 times, depending on the dose of the gene (one or two copies). However, many persons with the risk form of the gene are not affected. In the majority of cases of Alzheimer’s there is a key interaction of genes and environmental factors which determines who becomes affected and at what age. Although genetic testing can be done to predict risk it is not currently recommended, as genetic tests are not needed to have commitment to preventive measures.