Final answer:
The most likely diagnosis for the 16-year old boy described is Autism (ASD), a neurodevelopmental disorder characterized by impaired social skills and repetitive motor behaviors.
Step-by-step explanation:
Based on the symptoms described, the most likely diagnosis for the 16-year old boy is Autism (Autism Spectrum Disorder - ASD). ASD is a neurodevelopmental disorder characterized by impaired social skills, repetitive motor behaviors, strict adherence to certain rituals, and preoccupation with specific subjects. Individuals with autism may have difficulty making and maintaining eye contact, reading social cues, and feeling empathy for others. They may also engage in repetitive behaviors such as rocking or flapping their hands when upset.