In ancient times, marriage between close relatives was allowed. In ancient China, the issue of bloodline was highly valued, and it was believed that marriage between close relatives was a joyous occasion. Moreover, due to inconvenient transportation, it was difficult for men and women to have contact with other members of the opposite sex, so close relatives were very common in ancient times. However, due to the many health problems that may arise in the offspring of consanguineous marriage, China formulated regulations prohibiting consanguineous marriage shortly after its founding.
The reason why ancient close relatives and descendants rarely had problems
1. In ancient China, polygamy was practiced, and even if it involved consanguineous marriage, the possibility of the two having the same blood relationship was rare. Many cousin relationships were only based on status.
2. In ancient times, people were superstitious and focused on appearance. Children with health problems would be dealt with as soon as possible without letting others know, so there would be no records.
3. For true direct blood relationships, ancient people would deliberately avoid them.