[NickSharp]

There's strong evidence that all life on this planet can trace back to a single strand of DNA, which evolved exactly once in our billions of years.

For example, if I understand this correctly, a random jumble of DNA as you describe would have a 50/50 chance of twisting to the right or twisting to the left. And yet all life on earth uses DNA that is "right handed" twisting to the right.

[WClayFerguson]

The fact that life is right-hand twist DNA probably means left-hand was unsuccessful due to chemistry either in itself or in the environment, because an inversion of a molecule (chirality, twist, etc) means it will behave completely differently chemically. So left-hand twist can exist, but not necessarily in a way that can build life...even if it's able to initially replicate.