A fault which is related with forefathers is called "PITRADOSH". Meaning of `Pitra’ is not the father but our ancestors, they are those ancestors whose soul has not yet attained salvation and have a special affection for their dear ones. If religious rituals are not performed properly due to any reason, then it is called "PITRADOSH".
In this world almost all the religions consider that, after the death of human being only body gets destroyed but soul never dies. According to "Geeta" as we wear new clothes after the bath similarly after the death our soul leaves one body and moves into a new body.
Like human beings our forefathers also feels the Happiness, sorrow, love, affection, hunger and thirst. After the death of the person if there family member had not paid proper tribute or homage to them they will be annoyed with their dear ones.
Generally these forefathers have divine powers and they are worried about the success, happiness and wealth of their family members, they feel weakening of their powers when commemoration is not done properly for them, then inspite of their willingness they will not help their family and over and above if they get angry with their dear ones, then the family members might face many difficulties.
Because of the "PITRADOSH" a person can suffer a lot of difficulties in their life, like illness of family members, mental disturbance, no birth of child, lots of girls in family and no son, difference among opinion of family members, instability of earning, enough income but it's not stable, many debts, faltering at the critical moments of life, making efforts but not getting appropriate results, accidents and sorrow in the old age, etc. Many people have ‘kalsarp yog’ in their "Kundali", the major reason for this ‘Kalsarp Yog’, is "PITRADOSH", because of this human beings have to face a lot of problems and instabilities in their life.
Every religion has described the Importance of Forefathers.