[BuckRogers]

They must like rounding up. I guess it depends how they refer to it in their language. If it's "he's in his 1st year", that's a big difference from, "he's 1 year old". I'm wondering if the parent comment simply doesn't know Korean or only knows it somewhat to misconstrue the culture behind this.

It could be though that Korea simply never encountered the Mayan or Arabic civilizations as most did encounter one of those two in history, who are famously known to have independently discovered the concept of zero.

Birth of an array can only logically be defined as index zero, the same as a child. The concept of zero was not universal globally and Korea is pretty isolated.