Genes aren't the only factor. Because you inherit one APOE gene from your mother and another from your father, you have two copies of the APOE gene. Having at least one APOE e4 gene increases your risk of developing Alzheimer's disease. If you have two APOE e4 genes, your risk is even higher.
Compound Time Signatures In compound time signatures, the beat occurs on a dotted note and is divisible by three. The most common compound time signatures are 6/8, 9/8 12/8.
He then explains time signatures, discussing common, compound, and asymmetrical time signatures, as well as double time and half time, and how to choose the time signature for a song. Next, he discusses the concepts of feel and timing, including dynamics, accents, articulations, tempo changes, swing, syncopation, polyrhythms, and playing ahead of, on, and behind the beat.