The idea that we “knew” our friends, families and especially our future spouses in the pre-existence was first dramatized in the novel “Added Upon” by Nephi Anderson (in 1898)! Then, in the 1970’s, there were two popular musicals that were seen by hundreds of thousands of Church members: “My Turn on Earth” and “Saturday’s Warrior“.
“My Turn On Earth” didn’t really get into the whole relationships-in-the-preexistence thing, but “Saturday’s Warrior” sure did! One of the sub-plots was rebellious teenager Jimmy arguing with his parents over their decision to have another baby when the world is on the brink of overpopulation. But at the beginning of the play, we have already seen the whole family in the preexistence, and Jimmy was especially close to his future-little sister, whose birth he is now protesting! Oh the irony! And the older sister whose spirit loved to dance in the spirit world is born to a body confined to a wheelchair. Oh the tragedy!
There is also a common feeling among many parents that they are visited by the spirits of their “future children”, as if there were actual spirits in the preexistence anxiously waiting for those two specific people to concieve so they can be born into that specific family. I’ve heard several stories told over the years in different settings.
But the idea crumbles upon the slightest investigation. Just think about it. A conception isn’t the result of a single encounter between a man and a woman. No, a conception is the result of an impossibly long chain of trillions upon trillions of individual choices made by all the billions of people who have ever lived on this Earth. And for all the trillions of variables that are involved, very few are actually under the control of the mom and dad.
At the very least, their parents would have had to make the correct choice regarding the timing of their births, and then their lives would have to intersect at the right time and place for a relationship to spark. And this assumes intentional conception. If we factor in the countless unintentional conceptions, whether they be between a married couple, or something more casual, unconventional, or involuntary, any carefully set plans from before this Earth would get mixed up beyond belief once the slightest variable gets set the wrong way.
If we truly wish to believe that we could have known our Earthly families beforehand, then we have to imagine a flowchart of the billions of births being designed before Adam and Eve were on the scene, and every conception and birth being carefully monitored to ensure future generations come through the queue in the proper timing and order.
But, as with many ideas in religious traditions, this one will never die. It just sounds too good, and makes too many people feel warm and fuzzy. And it just seems to make sense.