There could be serious damage to their family relationship. It might lead to feelings of discomfort, shame, and guilt within the family. Also, if it becomes public knowledge, it can bring social stigma to the family.
The son may experience long - term psychological trauma. It can distort his view of appropriate relationships and boundaries.
The consequences are numerous. For the son, it can cause confusion about his role and the nature of family relationships. Socially, it may lead to ostracism if discovered. From a psychological perspective, it can plant abnormal and inappropriate ideas in the son's mind, affecting his future relationships and mental health. This situation violates basic moral and ethical principles that are fundamental to a healthy family and society.