If a father is permitted to marry his deceased son's wife, in fairness a son should be allowed to marry his deceased father's wife.

I presume that there is a law in the United States or in some of the states against marriages within the prohibited degrees of consanguinity and affinity, but I confess that the more I study the subject the more I am confused as to what is or what is not within the prohibited degrees.
In China the law on this subject is extremely rigid, and consequently its infraction is exceedingly rare; I have, as a matter of fact, never heard of the marriage laws in China being broken.

In "Liao Chai", a famous collection of Chinese tales, it is recorded that a young widow married her son and moved to another part of the country, so that their identity and relationship should be concealed.

They seemed to have lived very happily together.

After many years, when they had had children and grandchildren, their true relationship was accidentally discovered.