Reasons we are reborn as a family:

kindness, revenge, and debts.

The causes of affinity are manifold. The Buddha grouped them into four categories: to repay kindness, to exact revenge, to collect a debt, and to repay a debt. If a particular affinity is powerful, we’ll be reborn in the same family. If lighter, as friends. Lighter still? Then we’ll interact to some degree.

Say we had been kind to someone in past lifetimes, this person could now be in our family to repay that kindness. When we encounter trouble, she is the one helping us wholeheartedly.

What if we had been unkind? We will have a person who dislikes us, so often insulting and even slandering us. He has come for revenge.

If the person defrauds or robs us of our money or belongings, she is collecting a debt.

If someone helps us make money so that we become well off financially, he is repaying a debt.

Examples of cause and effect for the four basic kinds of affinities are numerous, but we can appreciate the general idea—we need to nurture good relationships and resolve enmities.