Pretty surely, the genetics is the least important part of it. Snakey grain is just a reflection of the shape of the log or branch, which is caused by light availability: all plants are phototropic: they grow towards the light. As light conditions change (because other trees/branches are also growing nearby and catching light), so does the direction of growth.
Nearly all wood can be grown to be pipe-straight, if you give them good light conditions and prune side branches immediately.
Another way of causing snakey grain is by just pulling a branch or sapling in a desired shape or direction and let it grow. Once you have additional lignification (one year later) the basic shape is determined. This way you can probably grown branch or sapling bows immediately in a RD design :-)
