Central Forensic Science Laboratory, Kolkata-700 014, India E-mail : sujitclahiri@yahoo.com Manuscript received 03 December 2015, accepted 29 January 2016 True explanations or reasons for oncogenesis or human cancers are still illusive though a number of theories have been advanced but cancer has become an undeterred menace. There is no specific oncogenic virus as such which can account for all types of cancer and probably cancer is not a virus related diseases but viruses act as secondary reason in 15–20% cases of cancer. An attempt has been made to provide an alternative non-conventional theory of ‘oncogenesis’ based on (i) Water and its structural modifications leading to structural destruction or structural changes in proteins DNA, RNA etc. (ii) Oncogenic spots or sites and oncogenic compounds. (iii) Virus and virus related infections. (iv) Enhanced microbial activities of eukaryotes and particularly of aggressive prokaryotes and human microbiomics. It is to be noted that the ‘seeds’ of oncogenesis are unknowingly in human biosystem. These seeds or microbes perform their specific biologic and metabolic activities in human biosystems but become aggressive due to extraneous aberrations in human body to cause cancer.