Certainly, "who" a person is, is a dynamic process. However, I strongly suspect that things like nutrition, social interactions and sleep are things we're adapt

Certainly, "who" a person is, is a dynamic process. However, I strongly suspect that things like nutrition, social interactions and sleep are things we're adapted to self-modulating, so these are ways we can "consciously shape ourselves", give the old-us the opportunity to create the new-us. But a drug with an unexpected affect on personality seems like the opposite of this.