A: There are many factors standing in our way of achieving fusion while residents of Urantia; for the vast majority of us, it is a goal that will likely have to wait until after we pass through to the other side. For the planet as a whole, we have to be far closer to the ages of Light and Life before we begin to see fusion as a regular occurrence.
The Urantia Book does have quite a lot to say about the parenting experience and family life—from God the Father in the spiritual realms, down to the basic human social unit known as the family.
About the parenthood experience we learn:
(45:6.4) No surviving mortal, midwayer, or seraphim may ascend to Paradise, attain the Father, and be mustered into the Corps of the Finality without having passed through that sublime experience of achieving parental relationship to an evolving child of the worlds or some other experience analogous and equivalent thereto. The relationship of child and parent is fundamental to the essential concept of the Universal Father and his universe children. Therefore does such an experience become indispensable to the experiential training of all ascenders.
This is taken from the section called: "Adamic Training of Ascenders."
In it we also learn:
(45:6.6) All mortal survivors who have not experienced parenthood on the evolutionary worlds must also obtain this necessary training while sojourning in the homes of the Jerusem Material Sons and as parental associates of these superb fathers and mothers. This is true except in so far as such mortals have been able to compensate their deficiencies on the system nursery located on the first transitional-culture world of Jerusem.
So, you can rest assured that, even if you have not parented children while on earth, you will obtain this experience sometime in your eternal future.
As for parenthood being a requisite experience in order to fuse while on earth, I am not aware of anyplace in the book where this is discussed. But I can say that at this time, Adjuster fusion is rare on Urantia. As far as I know, only Enoch is of note as being the first (and possibly only?) mortal to have achieved this accomplishment. There may have been others, but I am not aware of them. Until our planet becomes closer to the ages of Light and Life, we will not be seeing many humans experiencing fusion with the Adjuster. But we will have ample opportunity to work towards this ultimate goal:
(112:7.3) Fusion with the Adjuster is usually effected while the ascender is resident within his local system. It may occur on the planet of nativity as a transcendence of natural death; it may take place on any one of the mansion worlds or on the headquarters of the system; it may even be delayed until the time of the constellation sojourn; or, in special instances, it may not be consummated until the ascender is on the local universe capital.
Since you are a man who loves God, I would not worry overmuch about the absence of children standing in the way of your eventual fusion with your Adjuster. And, parenting is an experience that you will have at some future time, even if you haven't had it before you leave this planet. So, enjoy your life—walk with God, and be of good cheer!"