> You like most of others, seem to have no idea as to how retroflex words came into existence in India, It's due to pronunciation practiced in Samved's Jaimini shakha. Not only in Tamilnadu but in other states also Jaimini followers use retroflex in their recitals.
So how do the other schools pronounce them? I have seen suggestions that the loss of the original contrast of Indic dental and retroflex nasals and sibilants was due to Dravidian languages having a 3-way contrast of dental, alveolar and retroflex consonants.
The very early Prakrit Pali shows clear signs of having *lost* the contrast of dental and retroflex sibilants. Where /ṣ/ rather than /s/ would force the presence of /ṇ/ rather than /n/ in Sanskrit, and Sanskrit rules would force /ṣ/ rather than /s/ (i.e. RUKI environments), Pali has /ṇ/ rather than /n/ even though it makes no distinction between /s/ and /ṣ/.
Richard.