By my study of existence and interpretation of a vision I was given I will say there is but one spirit that permeates every physical manifestation but there could be 700 million - in many of my writings I suggest 700 million, as I call spirit, "Timelines". Timelines are the sequence every manifestation incarnates on earth or metamorphose on other planes.
The vision was only a giant ball of string without ends and when I came out of it spirit revealed that as existence - neither all nor my own individual's was said is why I use 700 million as 10% for civilization's end population - which has no beginning nor end.
After being revealed I was my own son, his son of the same name and my parents with daddy having my first name because of karma - reaping and sowing - I sought how is that possible. I used the "giant ball of string" as an infinity folding back and forth in our earth plane existence. Some philosophies call that multiple incarnations.
We enter earth as, using Genesis 1, water until we have manifested as every drop of water we will use during our earthen sojourn before incarnating as matter, microbes, plants, insects, birds, fish, and all other animals before becoming man. As man we incarnate as every attribute and condition seen and unseen among man before all of that information is brought to our remembrance when we become one of the "10 virgins" [10% of today's population meaning in our timelines is 10% of all of earth and of its life types] (Matthew 25:1-13).
Therefore the only reason we miss our love ones so much is because we haven't learned to live without attachments.