" Fears can increase at this age for many reasons. First, there is simple conditioning: Whatever was around when you were overaroused became associated with overarousal and so became something more to be feared. Second, you may have realized just how much was going to be expected of you, how little your hesitations would be understood. Third, your sensitively tuned “antenna” picked up on all the feelings in others, even those emotions they wanted to hide from you or themselves. Since some of those feelings were frightening (given that your survival depended on these people), you may have repressed your knowledge of them. But your fear remained and expressed itself as more “unreasonable” fear. "

― Elaine N. Aron , The Highly Sensitive Person: How to Thrive When the World Overwhelms You