Absolute or perfect pitch is obviously a rare trait. Only about one in 10,000 people have it, and it seems that perfect pitch is higher in East Asian populations, in blind musicians, and some autistic people.
Genetics plays a role. Studies show that people with absolute/perfect pitch were often in a family where another family member also had absolute pitch. and as one professor s said, “It’s nature and nurture, like everything else.”
Well, as far as the nurture component, although rigorous musical training is requisite for the development of “perfect” pitch, more importantly is starting training from the age of 6 or 7. Scientists believe that is a critical development period where the brain has the ability to wire auditory patterns into memory and configure simple recognition of tones into “pitch labeling”. Sort of like playing with a baseball as a child make him a better pitcher as an adult. And the idea of (musical )” pitch labeling” is like understanding a language: the earlier the better! Speech and musical sounds can be interpreted by the brain in a similar manner.
The tonal languages like Mandarin and Vietnamese made their musicians more able to have “perfect” pitch, and pitch conveys meaning, and is an essential component of the language.
Basically, the idea that learning “perfect pitch” can only take place in childhood has been challenged by research.
A Harvard University Professor used young adult males with no musical training were prescribed with Valproate and assigned music learning tasks. By the end of two weeks, the group taking Valproate had significantly improved their ability to identify tones in a “musical pitch” test. So perhaps I the future, those who are “tone deaf” when in the shower will end up being the next Pavarotti!