Musical engagement is influenced by both environmental and genetic factors. Here, we explored nongeneticinfluences on musical engagement by performing semi-structured interviews of 10 Swedishmonozygotic twin pairs that were highly discordant for piano practicing. The interviews were organizedinto five sections – (i) perceived reasons for the discordance; (ii) childhood differences in specific musicrelated variables; (iii) strong memories of music; (iv) the perceived meaning of music in life and forhealth; and (v) language interests – and analyzed using response categorization. The playing twins froman early age found music more interesting and enjoyable than their co-twins and also gave richer andmore elaborate descriptions of the meaning of music in life, in several cases emphasizing that music wasimportant for their personal identity. In line with this, an analysis of previously collected web questionnairedata showed that the playing twins had a significantly higher openness to experience and pronenessto experience flow during musical activities. In contrast, the twins reported essentially no within-pairdifferences in the musical engagement of their peers, parental support, music teacher, ensemble playing,public performances, and their interest and aptitude for languages. The interviews gave no indication thatthe differences in musical engagement were caused by systematic environmental influences that wereconsistent across twin pairs. Rather, the respondents presented a wide range of different explanations fortheir discordance in musical activity, suggesting that the remaining influences on musical engagement,when genetics and family environment are controlled for, may be highly individual and idiosyncratic.