Though, a new and plausible terrestrial origin of life hypothesis:

Methane + Gamma radiation => Guanine && Earth thunderstorms => Gamma Radiation https://news.ycombinator.com/item?id=42131762#42157208 :

> A terrestrial life origin hypothesis: gamma radiation mutated methane (CH4) into Glycine (the G in ACGT) and then DNA and RNA.