Congenital amusia (tone deafness) is a lifelong musical disorder that affects 4% of the population (single estimate based on a single test from 1980); it is more 1.5pct of pop. and is highly heritable

Peretz, Isabelle, and Dominique T. Vuvan. 2020. “Prevalence of Congenital Amusia.” PsyArXiv. February 12. doi:10.1038/ejhg.2017.15

Abstract: Congenital amusia (commonly known as tone deafness) is a lifelong musical disorder that affects 4% of the population according to a single estimate based on a single test from 1980. Here we present the first large-based measure of prevalence with a sample of 20 000 participants, which does not rely on self-referral. On the basis of three objective tests and a questionnaire, we show that (a) the prevalence of congenital amusia is only 1.5%, with slightly more females than males, unlike other developmental disorders where males often predominate; (b) self-disclosure is a reliable index of congenital amusia, which suggests that congenital amusia is hereditary, with 46% first-degree relatives similarly affected; (c) the deficit is not attenuated by musical training and (d) it emerges in relative isolation from other cognitive disorder, except for spatial orientation problems. Hence, we suggest that congenital amusia is likely to result from genetic variations that affect musical abilities specifically.