There are roughly 7X10^27 atoms in a 150 lb. human body. Thats 7,000,000,000,000,000,000,000,000,000 or seven billion billion billion atoms. Thats a lot of atoms.
Now these atoms come from everywhere. The things we eat, the things we come in contact with, the air we breathe and those atoms and molecules that we are born with. That includes atoms that our mothers and fathers ate,breathed, touched and were born with.
Given the nature of atoms and molecules and the kinetic laws and the laws of statistics, the atoms that compose our body come from, literally, everywhere and every time. We have, within each and every one of us, a little piece of the entire history of the planet.
It is more then likely that we have atoms of our grandparents within us. Similarly we have atoms of their grandparents, and their grandparents and their great-great-great-great grandparents. We have parts of Ceaser and parts of Napolean and parts of Adam within us. We have atoms within us that were present at the great flood and at matan Torah. We breathe the air that they breathed then and eat the molecules of proteins and sugars and such that they ate. Or at least composite molecules. This interconnectedness is a fact of nature according to the laws that we live by. We are directly related to the past, present and future in miniscule ways that we cannot escape. Every time we go somewhere or eat something or kiss someone we take a part of them with us and make it a part of ourselves for the rest of our lives.
Take that how you like. This idea can mean different things to different people. Just something that was rumbling around in my brain at 3:45 this morning.