Thampi was born at Haripad, Alappuzha District, on 16 March 1940 to Kalarikkal Krishna Pillai (from Thonnackad near Mavelikara) and Karimpalethu Bhavanikutty Thankachi (From Karimbalethu Koyikkal Kottaram Haripad, related to the Royal House). In an interview, he stated that his ancestors shifted from Chirakkal in Kannur district to Haripad. He was the third of five children born to his parents, following two elder brothers and preceding a younger sister and a younger brother. He completed his schooling from Haripad government school. He is a graduate in mathematics from Sanatana Dharma College,Alappuzha and civil engineer, graduated from Institute of Engineering Technology, Chennai and Govt. Engineering College, Thrissur. He also did refresher courses in Architecture and