Some fatty acids (lawyer warning here: "this only applies to satutated linear (unbranched) fatty acids in certain life forms on Earth.") have a 2C homologation pattern because of how they were built up by enzymes. (Fatty Acid Synthesis - FAS pathway. Although there is another pathway at high pressures.)
That might give a pattern in.the MS that could be considered a biosignature - a hint of something exciting.