Final answer:
The son-in-law on the life of his father-in-law does not have an insurable interest.
Step-by-step explanation:
A person who does not have an insurable interest is the Son-in-law on the life of his father-in-law. An insurable interest refers to a financial or emotional interest in the life or well-being of the insured person. In this case, the son-in-law does not have a direct familial or financial relationship with his father-in-law, therefore he does not have an insurable interest.