To achieve the goal of precision medicine, not only do different molecular profiles need to be understood in disease populations, but they must also be understood in the context of healthy populations. This especially applies to the stability of molecular profiles among healthy individuals over time, as this will clarify what qualifies as a ‘normal range’ of clinical parameters in health and disease research. The following study by Tebani et al. (2020) conducted a longitudinal analysis of the blood profiles from 100 healthy individuals to understand how they varied both between different individuals, and within an individual over time.