The Trio San Antonio is more of a dynasty than a trio, with branches spreading out through more than several generations of musically talented family members. More important, the group represents a kind of historical source for what has come to be known as the norteño sound. This genre is a blend of Mexican songs from the northern regions of the country, such as Tamauillipas and Nuevo Leon, and the accordion styles of the German immigrants who settled in Texas. In the first decades of this music's development, the accordion became the lead instrument, replacing the clarinet, f...