I am looking for a young adult book that I read between 1983-1990. (It may be marginally sci-fi or dystopian, I don’t recall.)

The story is: A boy/teenager’s mother disappears. As he tries to find her, he comes into his own skill-set (maybe as a mathematician, scientist or problem solver — something.) In the end, he finds his mother, and she explains that she is part of a group who intend to start a new society or colonize off planet — something along those lines. She left her life behind and vanished in order to begin preparations with the group because the time to start this new colony or society was drawing near. (I believe her skill is agricultural or scientific, etc)

The big revelation is that she couldn’t tell him about what she was doing or bring him along because every member of the group must have a special skill or contribution to make to this new society that they intend to form. She could only hope that her son discovered his skill and could follow the clues to find her. (Essentially, now that he has become worthy, they are reunited and he can be part of this new colony.)

Thanks in advance,
Jana P.