I don't really know about Arteries, but fingerprints and palm prints are decided by the way your hands are closed shut inside of the womb. This can depend on multiple factors such as position inside the womb, the embryo's response to a stimulus, the pressure inside the womb, et cetra.
Fingerprints can be different based on those factors and hence, monozygotic embryos can possess different handprints and fingerprints.
I honestly don't know about the bifurcation of arteries, though. It is something that should be determined by genetics and not environmental factors. A human can easily be born diseased otherwise.
RE: Why are we not spherical - Breaking the symmetry of embryo with Alan Turing.