My Brother Is Having Behavioral Issues. He Started Developing The

My brother is having behavioral issues. He started developing the following symptom when he was 6-7 year old
1) Irritable (Chidchida)
2) Improper behavior with relatives and family members
He is an engineer and was an average student throughout the academics. He inherited these symptoms from my father.
Due to all these, he usually suffers to sustain his job and often humiliated by relatives/employer.
Rude behavior with family members and not able to talk to others are the key symptoms.
age 32y