Expression of Genes Influenced By Behaviors

My brother seems to have many Reptilian tendencies. This can be seen in his energy, behavior and postures. I think I am his full blood sister and worry that my DNA may also be partially Reptilian. Do we all have some of this DNA and our behaviors cause the expression of it more? I do feel connected to the Pleiadians. I also can recall  having elf like ears in one of my lifetimes. Do you know what type of being this relates to? If new have the same parents, how can we be so different?