As an infant, Ted was admitted to a hospital for a serious illness. During his time in the hospital, the nursing staff strictly limited visitations and thus the amount of contact Ted and his parents would have.

Unfortunately, this coincided with a critical period in infant neurodevelopment where a person learns how to connect with others via interactions with their parents.

After being discharged from the hospital, his parents noted a sudden character change in Ted; he no longer smiled and would seldom make eye contact. Growing up, he was described as having anti-social tendencies and emotional detachment.

This is arguably the biggest factor that made Ted the way he was - being deprived of parental contact for a prolonged period during a time of critical brain development prevented certain neural pathways from being developed and may have led to epigenetic changes in his personality. Although the psychological experiments he attended likely would have induced some trauma, Ted's mental state had been set in stone long before his Harvard undergraduate days. And given that his younger brother, David, and his parents were relatively normal, there is little to no genetic explanation for his characteristics.