This is the second time I've seen this article or something similar recently. I don't think this is exclusive to Indian culture. A non-committal reaction, where you don't want to nod or shake your head "no" is common in other parts of the world. I do it and I'm neither Indian nor have I worked in India.
Not sure why this post is being downvoted but I agree with this.
It’s not entirely unique to India but its frequency/speed of wobble is distinct from others.
Perhaps it has to do with their languages. Most of the languages have up and down tone that goes along with the wobble.
