Special children (i suppose you mean differently abled children) are not due to soul choices. In fact the soul has to reach certain degree of development before it can impose its choices upon nature. It is the result of the action of Nature, her forces and the groves through which it moves. Differently abled children are generally soul sparks transiting from the animal to the early human stages. As a result there are gaps and deficits as a partially developed consciousness (from the human point of view) enters to fill a human body. The parents to which such a transiting soul attracted or carried by Nature is partly to give a certain kind of experience needed for its growth (child as well as the parent) and partly due to some affinity of vibrations. If we understand this it becomes somewhat easier to navigate through this. But most often emotional attachments, the desire for a good progeny, social inconveniences, the sense of a fruitless labour takes over bringing much suffering.
Affectionately,
Alok Da
