It was once thought that each cell in a person's body possesses the same DNA code and that the particular way the genome is read imparts cell function and defines the individual. For many cell types in our bodies, however, that is an oversimplification. Studies of neuronal genomes published in the past decade have turned up extra or missing chromosomes, or pieces of DNA that can copy and paste themselves throughout the genomes. (1)

Our neurons do not seem to all have the same genome. (2)

If it not the DNA sequence, then what "mystery" does rule our body? Could it be...something NOT in our body? Nuh! My free will based on my deterministic DNA-based body cannot accept that! 🙂