There is an old line of thought on this, that views DNA/RNA as crystals. Crystals branch out/reproduce in predictable or unpredictable ways depending on scale. At large scales a dry lakebed may seem a mass of randomly-aligned crystals but at the smallest scale each crystal is identical. They each formed from the same starting conditions from which random precursors settled into identical patterns. Such logic would suggest that DNA/RNA, if beginning in near-identical conditions, might also settle into nearly-identical patterns. At large scales the crystals would appear different and random but at the smallest scales life could well be similar or even identical... if one sees life as a form of crystal.