I souls
I will start off by stating a law of nature, that everything observable in existence has some sort of mass, from the densest star, to the weakest/smallest subatomic particle. No matter what it is, in order for something to exist, it has mass, can we all agree? Now, here is where I am going to get my first bit of backlash, probably from the scientific community: by using this logic, all of our individual memories, characteristics, personality traits, etc, everything that makes an individual (or animal) an individual, has mass. No matter how small or what it is comprised of. I am not entirely familiar with what the scientific community agrees upon as far as what a memory is comprised of, where it is a specific set of charges stored somewhere in the brain or a specific path of brain cells, but memories do exist. People are able to recall, sometimes in shockingly vivid detail, what places, people, and things look like without having the specific thing they are recalling right in front of them. So they must have essentially some sort of backup file that they are accessing to recall portions of data to attention. Whatever the information is, and however the information is being accessed, the information exists, and because it exists, it has to have mass.
Now that we have established that individualities exist, I will say that every definitely has a different individuality because not everyone experiences the same events from the same perspective, at the exact same time. So not only does a person have a measureable individuality, every person has an individuality that is by some form (maybe chemically compositionally, or electrically charged) different. {I want to take a pause and say that I cannot give out numbers. I am 18 and have not put 70 yeasr of research into this subject. However, if my logic and formulas are sound, why should that discredit me ?