In Trinidad where about 40% of the population is Indian (primarily from the south), many of those with curly or wavy hair put so kind of relaxer in it. My aunt (also Indian) has an Indian hair car salon in St James in Port of Spain and told me 80% of her Indian clientele straightens their hair! She has straight hair though, but she puts mild relaxer in my dougla cousins hair. Oddly none of the dougla I know minus that cousin do relaxer.
Dougla is the term for people who are half creole or half black and half Indian in Trinidad and Guyana.