When do insecurities develop?

I had a revelation: insecurities always come from external factors. When you're born, insecurity is a non-existent concept. From a baby to the world, there's nothing to be insecure about. But from the moment you are born, outside factors start throwing darts at you.

First of all, there are the natural elements that can make you insecure. Cold, heat, wind, animals, etc. Your brain reacts instinctively to threats. Bad experiences might lead to fear. For example, if you're driving in a car and suddenly hit a thick wall of mist, you'll get insecure about driving 130km/h.

The other major factor is social elements, a.k.a. other people and especially their opinions. I think the biggest insecurities we have in our heads come from other people. Especially their opinions. A baby just does things that are programmed in his brain. Things that help him to develop into a toddler. But at one point in life, the young and the virgin soul of youth will get spoiled. Maybe it's another kid at daycare. Maybe it's a parent who pushes a kid's development too hard, so that an insecurity develops about his or her abilities.

Somewhere in the early stages of a lifecycle, the first insecurities start to develop. Later in life, lots of insecurities stem from the confusing love relationship between men and women. That's well after a person already has insecurities. But when do the first insecurities develop? Is it already in the baby phase, or later in life? And how does it start? And what is the first insecurity?