Angelus

Angelus is a genetic implant developed by Abstergo Industries. Angelus is advertised to be applied to little children, allowing their mental status to be transmitted to a wrist band worn by their guardian.

According to Erudito, Angelus works with the latest nanotechnology and allows Abstergo Industries to regulate a person's hormone levels and brain functions from birth.

Reference

 * Assassin's Creed III