I would robustly disagree with "musical genius"! You're right though that the skills from viola & mandolin have the possibility to combine to make for a really good start on violin. But I have two reasons for getting a teacher - I'm hoping a teacher will help address issues quickly and speed up my progress, especially as our band has some summer gigs that I think would benefit from some fiddle-playing. Also, I've been convinced that folk is better learned by ear from a folk musician rather than from reading dots. My teacher does 1-1 lessons but also hosts group Zoom lessons, which is a nice way to learn and I expect after a few months I'll just do the Zoom sessions.