"You can call it magic or destiny," Melanie says. "When we first started, Justine was just 7 and Sofia was 13. But our family's history has always been clear to us."

Their singing touches people's lives.

They have sung in church for the fire fighters and volunteers who had the noble task of searching for victims of the Sept 11 tragedy in the US.

They have sung in orphanages in Rwanda and when they sang the country's national anthem, President Kwita Izina, was so moved that he gave Justin a cow from the royal herd.

"Touring lets us see the world and how The Sound of Music has affected people's lives," Amanda says.

Even as they travel, the Von Trapps do not neglect their studies and they have enrolled at major music schools - Sofia studying at Berklee College of Music and Melanie at Grove City College.

When asked if they ever wish to do something "cooler" than folk-singing, they say they are mostly into classical folk songs, though they like all genres.

They also do a bit of songwriting and improvise on old folk songs.