Learning a musical instrument is a bit like learning a language. You can learn just one, or you can learn more. As with languages, once you have the hang of one, it is easier to learn another. This is why Jane is able to teach piano, voice, guitar, flute, clarinet, saxophone, keyboard, and theory.
For lack of time, Jane never learned violin, but Lauren has, so she teaches violin for us. Our son Joseph is also now teaching cello. In time we expect to offer double bass as our youngest comes up to speed.