Tone deafness test and genetics

A study looking at tone deafness in large families found that people who are tone deaf tend to have relatives who are also tone deaf. The authors of the study concluded that tone deafness is largely determined by genetics. The fact that tone deafness runs in families could have other explanations than just genetics. For example, consider a family that lives near a toxic waste site. Many family members may get cancer, but shared genes are not the reason for the cancer-- the toxic waste site is. Families tend to share houses and lifestyles as well as genes. To get around this problem, researchers often turn to fraternal and identical twins. Identical twins share 100% of their DNA, while fraternal twins only share about half of their DNA. Both types of twins usually grow up together and share most of the same environment. If a trait is determined completely by genetics, identical twins should more often share that trait compared to fraternal twins. This is because they have the same DNA and fraternal twins only share half their DNA. On the other hand, if a trait is determined mostly by the environment, both types of twins should be equally similar to each other. This is because they share pretty close to the same environments. Researchers used a “twin study” to look into the genetics of tone deafness. They measured the ability of both identical and fraternal twins to pick out wrong notes in popular songs. They found that identical twins were more likely to both be tone deaf but it wasn’t 100%. There were plenty of cases where one identical twin in a pair was tone deaf and the other wasn’t. With some number crunching the researchers concluded that between 71 and 80% of tone deafness can be explained by genetics. The remaining percentage is likely due to things like how much the different families listened to music or if the kids took music classes.