A: As far as we know from the teachings of The Urantia Book, the only pre-planning of parents that has transpired over the million year course of human history was the selection of Jesus' earth parents--the three most promising sets of parents were identified and Joseph and Mary were chosen from among them to provide the incarnation of the Creator Son the best opportunity for fulfilling his pre-ordained mission. Normal human beings don't have pre-ordained missions that require fulfilling.
The purpose of the mansion worlds is to provide the remedial environment for whatever is lacking in this material life. People brought up in non-spiritual environments, such as in the Satanic church, can still develop spiritualized thinking--they still have guardian angels the ministry of the Spirit of Truth, Thought Adjusters--just as those raised under the best of conditions can disavow the spiritual reality of life. Environment has a strong impact but it can be overcome through choice.
At conception our personality , the potential for the person we're to become, most likely gravitates toward parents who might provide the kind of environment suitable for our development. But, through the vicissitudes of life, there's no insurance that life will unfold as might have been projected. So, in answer to this question, it would appear that basically no, parents are not pre-ordained; it's the luck of the draw and we learn to make the best of the circumstances into which we're born."