Started piano lessons at five years old, and violin at age ten. I was not quite big enough for a full sized violin, which is rather tiny, as you probably know. I knew this because I would have my right arm stretched out with arm fully extended, elbow straight, and there was still about 4 inches of bow left up at the top of the bow!!!
And it just so happened that my piano teacher was an excellent violinist as well. He taught me both instruments until I finished high school. Talk about serendipity! I dropped the piano lessons after high school, although I still play for my own enjoyment. Continued the fiddle through college and community orchestras. Got tired of it after 15 years and put it up.
I have small bones and I'm five foot two. My growth spurt only was about four or five inches at the most because when I was young I was all of five foot three. And I am much shorter than my parents (((SIGH))) I've seen large guys playing the violin but they had large but delicate hands.
I'm convinced you have to match the hands to the size of the instrument. I see five foot tall women playing string bass in orchestras and I can't figure out how they do it. I tried to play a viola once and thought it was heavy and hard to play. Also, your left arm is stretched farther out, so it's harder to hold up. And my brain can't handle alto clef, only bass and treble. That note on the middle line damned well better be a B or a D, and if it's a C, that fries my brain. I can't think in fourths either. I know people who can play violin and viola both and it baffles me.
Guess they made casts of Franz Liszt's hands and that's how they know.