According to Hindu legend, there is a belief that the family deity (Kula Deivam) will protect and save the family members for seven births (Ezhu Jenmam) in general. This article briefs about, the number of births, that is believed for the family deity to protect the family.
It is believed that seven births in Hindu mythology is equal to 7*7, which is 49 birth years (Jenma Aaandu) in total. The added result of 4+9= 13. This number is very important in terms of family dynasties.
When a person dies, spiritual ceremonies will be done on the 13th day for the soul to leave the earth and reach the heaven. Accordingly, it is believed that a family dynasty will have a total of 13 births.
A family will have the 'same family deity' for 13 consecutive generations, according to this calculation. After 13 generations of a particular family, it is said that there will be usually no upcoming descendants, as they will be perished due to natural reasons like death or accidents.
Therefore, in the Hindu mythology, it is believed that the family deity is a possession which will last for 13 births for the family.