What does it mean for two sons to be dark for life?

Although you have two sons, you can accept a dark life. There are two explanations for fortune telling: First, although there are two children, people with unknown diseases can live longer. Second, one of the two sons is illegitimate or adopted. Today it can be understood that one of the two children is an adopted son or adopted son. It can also be said that although there are two children, anyone with unknown diseases can die.