Forget about maximizing your children’s academic achievement and ability levels (which musical training does) and let's focus on what actually matters: being happy. Where does music fall into this picture?
Molecular biologist and neuroscientist John Medina, author of the Brain Rules book series, asserts that the single best predictor of happiness is having friends. There are a lot of things that can determine someone’s ability to make friends, and the depth of those friendships, but in his book Brain Rules For Baby, John Medina places the ability to discern nonverbal cues as paramount.
So what grants one the ability to understand nonverbal cues? Medina recommends saving up for ten years of music lessons for your child, citing research that showed that children with ten years of music lessons who started before age seven have lightning-quick responses to subtle non-verbal emotional cues. Children without musical training, on the other hand, were unable to even notice the same nonverbal cues.