Fear!
The primal fear!
We feel fear naturally... It is something that is engraved in all living beings!
Fear is an instinctual defense mechanism developed in the nature of humans itself!
The question of whether emotions are learned or we are born by it was never a mystery!
It was clear as the sky to everyone that we are born with all emotions.
The baby is born, upon being hit on his but he starts crying! It means he feels pain!
The baby cries when he feels hungry!
The baby laughed when he find something new!
We are all born we emotions, and the rest of our life is spent gauging which thing produces which emotion.
We know emotions by birth but we don't know what produces them!
Like a baby might be unaware that fire can cause him pain!
Once he puts his hand near the fire, he will feel the scorching heat and learn about the pain felt by fire for the first time in his life!
The baby knew pain already but he wasn't aware of what causes it...
Fear was the same!