Answer: Brandon may be diagnosed with Autism spectrum Disorder.
Step-by-step explanation:
Autism spectrum disorder (ASD) is a developmental disorder condition related to brain development that affects how a person especially children perceive his or her environment making such individual have challenges in socializing, communicating or interacting with other people which poses problems in social interaction and communication and behaviour.
Here, Brandon rarely speaks and has little interest in interacting with his siblings or parents. His interest seems completely absorbed by a few of his toys shows that his social and behavioural attitude is challenged which means having Autism Spectrum Disorder.