The Bodhisatta was once a son, nephew, and grandson of the same man in one thousand five hundred successive lives (five hundred lives for each relation) and he was then born into the same three relationships in another one thousand five hundred successive lives (again, five hundred lives each) to one woman.
In the Lifetime of the Buddha
One time while the Buddha was traveling, a stranger threw himself at his feet and called him “son,” asking why the Buddha had not visited for such a long time. This man insisted the Buddha should come to his house to see his “mother,” who likewise fell at his feet and criticized him for being away so long. After the Buddha accepted their hospitality and gave a sermon about old age, he left.
The disciples traveling with the Buddha at the time wondered why this family did not know who the Buddha’s real parents were and why the Buddha did not comment about it. To end their confusion, the Buddha told this story explaining his relation to the man and woman in earlier births.