There has been growing interest in the origins of musical interests and talent, explaining the recent accumulation of twin studies on these topics. It is worth noting that several twin-based conferences, such as the 2014 International Twin Congress in Budapest, Hungary and the 2017 Twins Festival in São Paulo, Brazil featured identical twin singers at their closing events. These are not isolated events — during a trip to New York City in August 2017, I attended a stunning musical performance, Songbook Summit, a four-part revue of the music of Cole Porter, Ira and Arthur Gershwin, Howard Arlen and Richard Rodgers, created by and featuring twin jazz musicians, Peter and Will Anderson. Their matched abilities, stage presence, and musical versatility (the twins seamlessly alternate between playing the clarinet and saxophone) closely match what twin studies have been revealing about musical skills, namely that both genetic and environmental influences play a role. A selective sampling of studies is presented below, followed by an interview with the Anderson twins.
Absolute pitch, or perfect pitch, is a cognitive skill, defined as the ability to correctly name any musical note that is heard, or to sing any musical note correctly without assistance (Merriam-Webster, 2017). Absolute pitch improves with training, but whether the training produces the skill or having the skill motivates one to practice has been an unanswered question. Evidence of genetic effects was found among siblings in a family aggregation study, but the possibility that unknown environmental events explained the result could not be dismissed (Baharloo et al., 2000).
Based largely on the Baharloo et al. (2000) finding, Theusch and Gitschier (2011) conducted a twin study and segregation analysis of absolute pitch. Genetic factors were indicated by the greater resemblance shown by 14 monozygotic (MZ) than 31 dizygotic (DZ) twin pairs who completed an online survey in which they answered questions about their own absolute pitch and that of their siblings. It was also concluded that absolute pitch is a complex trait, most likely affected by various environmental, epigenetic, and stochastic factors. Aside from the small sample, the results should be viewed cautiously, given that the zygosity determinations were sometimes based on twins’ self-report and number of placentae, which may be misleading.
Finnish investigators extended this work in a twin study of musical pitch and rhythm melody (Seesjärvi et al., 2016). Three online musical tasks were performed by 69 MZ twin pairs and 44 DZ twin pairs, as well as 70 individual MZ twins and 88 individual DZ twins. The tasks assessed Scale (detection of pitch changes in a two-melody comparison), incongruities in Key (off key perception in a single melody), and incongruities in Rhythm (off beat perception in a single melody). The results showed that these various facets of musical ability are differently affected by genetic and environmental influences. Specifically, Scale was mostly affected by additive genetic effects (58%), Key was largely affected by shared environmental effects (61%), and Rhythm was largely affected by non-shared environmental effects (82%).
The extent to which practice contributes to musical talent has also been addressed via twin studies. Hambrick and Tucker-Drob (2015) found evidence of genetic influence on music practice. In particular, they reported a gene × environment interaction effect in that genetic effects on musical skill were most salient among individuals who do practice. They used existing data from twins who completed a self-report survey concerning music practice and music accomplishment as part of the National Merit Twin Study (NMTS) conducted by Loehlin and Nichols (1976). A related study included interviews with 10 Swedish MZ twin pairs discordant for music practice (Eriksson et al., 2017). The twins, who differed by a total of at least 1,000 practice hours, indicated various, non-systematic reasons for this difference, among them greater openness to experience by the playing twin and greater proneness to experience flow while playing. Finally, a twin study by Mosing et al. (2014), also with Swedish twins, found genetic influence on music practice (40–70% heritable), and that the extent of practice did not affect ability within MZ twin pairs.
My interview with twin jazz musicians Peter and Will Anderson was an excellent opportunity to explore some of these findings. I met up with them on September 30, 2017 at the Vibrato Grill in Beverly Glen, California, founded by jazz musician Herb Alpert, where they were scheduled to play that evening. It was just one of their stops on an extended tour throughout the United States.
The 30-year-old twins were born in Washington, D.C., but grew up in the nearby suburb of Bethesda, Maryland. Peter was born first by cesarean section with a birth weight of four and a half pounds. He was followed 10 min later by Will, the larger twin, who weighed five and a half pounds.
The twins’ father is a professor specializing in Chinese history at Georgetown University and their mother teaches English and grammar to non-native English speakers. They have an older sister who earned a degree in economics and now works for Microsoft in Seattle, Washington. Neither of the twins’ parents played a musical instrument, but a paternal aunt was a pianist and their maternal grandfather (whom they never met) was a ‘jazz fanatic’. The only direct musical influences in the twins’ home were their mother's strong appreciation for jazz, her support of their musical interests, and the availability of her recordings of favorite artists, such as Benny Goodman. The twins’ sister, who is older by 8 years, played the violin in high school when her twin brothers would have been in the elementary grades.
The twins’ first instrument was the clarinet. According to Peter, both he and his brother Will had always liked music and practiced constantly. Having a twin brother nearby helped to develop their musical talent because if one twin was playing video games and the other was practicing, the first brother would be motivated to practice, as well; practice is a behavior with demonstrated genetic components, as indicated above. The twins were competitive, but in a good way, just ‘trying to keep up with one another’. I have heard such sentiments before, especially from elite identical twin athletes who believe that what one of them achieves can be matched by the other (Segal, 2000). They are usually correct. The Anderson twins eventually became adept on other instruments, such as the saxophone, as shown in Figure 1.
FIGURE 1 Will (left) and Peter Anderson. Photo credit: Lynn Redmile.
In high school, the twins studied with music teacher Paul Carr, whom they credit with being an outstanding mentor. Upon graduating, they hoped to go to New York, a dream that was fulfilled when both were admitted to the prestigious Julliard School for the performing arts, located at Lincoln Center, where they completed BA and MA degrees. Throughout their years in school they were ‘great together’, with friends, teachers, and classes in common; they have never been separated for more than one month. Now they write, produce, and record music together, and believe that each brother contributes equally, although differently, to the finished product. For their production of Songbook Summit, Will completed the narration and research, while Peter was responsible for the musical arrangement. They love performing together, exuding ‘great energy’ whenever they do, and want to continue to do so in the future, perhaps overseas where appreciation for American music runs high. But in the jazz world, people often play alongside others, and while the twins do that too, they would rather be playing next to their brother.
The twins’ musical interests and talent are not their only similarities. Both describe themselves as very athletic — when they are not performing they often run in New York City, and growing up, they played soccer, basketball, and baseball and ran track. They are also both very organized, a quality that no doubt fuels their success.
However, twins are never exactly alike, and Will and Peter are no exception. Peter plays the tenor sax and Will plays the alto sax. Will has also played the flute for many years, an instrument that Peter ‘keeps in the closet’. While on tour, Will rents the cars and Peter reserves the hotels. Will is left-handed like his sister, while Peter is right-handed, and Peter is married while Will is still single. Felix Lemiere, who occasionally accompanies the brothers on guitar, observed that many people cannot tell Will and Peter apart physically, but jazz musicians can tell them apart musically. Will explained that inflection (a change in pitch or tone) can make a difference, and Peter followed up, saying that outside factors, such as hearing a particular performance or artist, can influence one's own musical rendition. I was reminded of Prof. Thomas J. Bouchard's view that identical twins are like different versions of the same song.
The Anderson twins sound a lot like MZ twins and they believe that they are — that's what their doctors have always told them — but I am not so sure. According to Will, if someone meets just one of them and comes to know them well before meeting his brother, then they have no difficulty distinguishing between them. Alternatively, if someone meets them at the same time then it becomes harder to tell them apart. Interestingly, I had a different experience — expecting the twins to be identical, as noted in their Songbook Summit biography, I was struck by their different facial structures as I watched them perform together. At our meeting at the Vibrato Grill, I asked them to complete a standard zygosity questionnaire (Nichols & Bilbro, 1966), and while it classified them as MZ at the highest level of certainty, I am not fully persuaded. The twins are interested in having their DNA analyzed using the test kit I brought with me, and the results should be available within a few weeks. The twins have admitted that they will be ‘shocked’ if they prove to be non-identical.
The Andersons offer researchers a good lesson in the best way to conduct zygosity assessments. I am reminded of Race and Sanger's (1975) insightful words on this topic: ‘For many years, Mr James Shields of the Genetics Unit at the Maudsley Hospital has been sending us samples of blood from the twins. We find that the blood groups practically never contradict the opinion of such a skilled observer of twins’. Despite their overall accuracy, scores on twin-typing questionnaires can be misleading in individual cases. DNA testing is, of course, the best scientific method for twin pair classification, but when it is not possible, I believe the impressions of experienced researchers count.
I have decided to give away a complimentary signed copy of my forthcoming book, Accidental Brothers, to the first reader whose judgment of the twins’ zygosity is correct, based on the photograph shown in Figure 1.
The Anderson twins’ website (http://peterandwillanderson.com) includes additional information and photographs, as well as a calendar of their upcoming performances. I want to hear them next when they perform again at the Appel Room at Lincoln Center.