Favored Child Transformed to Caretaker?

In browsing through the New York Times's New Old Age Blog, I found this intriguing article on the relationship between a parent's favorite child and who ultimately becomes the parent's caregiver.

A new study, led by Dr. Pillemer, proposes that parents are more likely to choose the favored child to take care of them in their old age. Before making this assertion, Pillemer also cuts away the illusion that every parent loves their children equally. After interviewing seniors, Pillemer discovered that virtually all of his interviewees were able to name a favorite child. Ironically, middle-aged children were often incorrect in their guess of who was the favorite child (most of them picked themselves when it was actually a sibling who won the majority of their parents' praise).

Pillemer's argues that an aging parent will depend on the favored child to take care of them as they face old age, even if that child is troubled or unreliable, because the parent feels more comfortable with him/her. However, I think Pillemer fails to account for the practicality of care-giving. If the favored child lives further away, then it is more pragmatic to depend on the child who is located closer. While I don't have statistics on this, I would imagine that pragmatism is often more valued than intuition when it comes to care-giving in old age.