I spent some time talking with a friend the other day about just how hard it is to play the violin. Not so much because learning to put your finger in the right place and produce the right pitch is a major problem - children gradually learn how to do this, and learn what the correct sound is and what isn't.
Nor is it a matter of the bowing, which is like learning to juggle by adding more and more items to what you're throwing around. Anyone can do it...!
No, what we were talking about is the sheer awfulness of the way violins have to be held, and the way the left hand has to twist back on itself in order to put its fingers on the strings. At speed. Accurately. For long periods of time. (We watched the 45-minute Sibelius Second Symphony being played last night. The violinists were on the go almost all of the time; only the horns played less, I think!)
Viola players have this to contend with too, but go down the scale to cellos and basses and you find they have a much easier road to hoe. Their left hands are in a relatively natural position. And they don't have to keep their right hand - the bow hand - up in the air all the time either. So if you're going to play a stringed instrument go for the cello or the bass. There's a bit of stretching involved for the left hand, compared to violinists and viola players, but that's still easier than dealing with two hands/arms twisted up in front of your face.
Of course musicians who play string instruments in the orchestra aren't the only ones who have to suffer the backwards left hand problem (unless they're left handed, in which case they may suffer the backwards right hand problem, if you're still with me). People who play acoustic guitars, for instance, also have to cope with this, though at least their right hand isn't struggling with a bow at the same time. They only have a pick (something that's likely to cause arthritis in the long run through the concentrated hold on such a small device) or they use the fingers to strum. Once they've got past callouses, they're okay.
Sadly, while it might seem like a good idea for violinists/violists to situate their instrument somewhere else, the practical fact of the matter is that under the chin is the best place, for bowing, for support and for poking your neighbour in the eye if you're sitting too close to each other.
But it has health problems. Here's an old piece about tendonitis and musicians and a more recent piece about musicians' cramp, or dystonia.
Maybe it might just be better to encourage children to take up a different instrument....