Why is it the karma of some people to be born mentally retarded or physically handicapped?
When you follow spiritual life you develop purity and clarity of mind and body, and then certain rules govern your psychological and biological processes. But if you follow a particular culture which is alienated to spiritual discipline and ideals, it will ignore all the systems and rules which control the psychological, biological and emotional processes that govern the whole lifespan. In such cultures, there is untold suffering, and in every generation children are born handicapped or with a lower mental capacity.