The answer to the riddle is your sister, although the wording is designed to be confusing at first. The phrase, “I am your wife’s mother-in-law’s daughter,” sounds complicated, but it becomes much clearer when you work through each family relationship one step at a time.

Start by identifying your wife’s mother-in-law. Since your wife is married to you, her mother-in-law is your mother. That means the first part of the riddle simply refers to your mother, even though it uses a more complicated description to disguise the relationship.

The second part says the person is your mother’s daughter. In the traditional version of the riddle, that points to your sister—the daughter of your mother who is being described. The puzzle works because it encourages people to overthink the wording instead of recognizing the straightforward family connection.

There is one small exception. If the person solving the riddle is a woman, she is also her mother’s daughter, so the answer could technically be herself. Even so, the classic and most widely accepted solution is your sister, since the riddle is generally intended to test your ability to follow the chain of relationships rather than look for alternative interpretations.