Origin story
Each family lineage preserves its own kuladevata, the guardian deity of the household, honoured at weddings, naming ceremonies and family festivals. The deity is often a local goddess or a form of Shiva or Vishnu, worshipped at a family shrine or an ancestral temple.
The family lamp, the kalash and the ancestral shrine mark continuity, protection and gratitude. In Kerala the kuladevata is remembered before every important step in life, and the annual family pilgrimage to the ancestral shrine keeps the bond between generations alive.
Source: Wikipedia: Kuladevata — https://en.wikipedia.org/wiki/Kuladevata