Is karma real?

Although the concept of "karma" has religious roots, it seems to contain a grain of truth, namely that people will, in the end, get what they deserve. So if a father is mean to his children, he will find them unwilling to help him when he suffers a health crisis in his old age. In contrast, children raised with love and kindness will be eager to help their ailing father. Is this understanding of karma true? Is this a concept that rational people might or should use in their moral thinking?