Greetings for49,
After reading the reference supplied by Chris, it might be worth asking yourself the question, how would kammic forces know who would be a good parent and a bad parent, and how to direct embryos to "the parents they deserve".
Frankly, this seems a little far fetched to me... it seems to rely on some inate sense that there must be some kind of universal justice at play... and that everything must balance out in the end.... but if you look at the references Chris provided, you'll see that this is not what kamma is about.
Metta,
Retro.
