First, a little backstory.
Yaakov (Jacob) has 12 sons. The second to last, Yosef, was the favorite, and bred jealousy from his older brothers. They sold him to merchants, who then sell him in Egypt as a slave. While there, he’s pretty successful, but if framed for a crime and thrown in jail. While in jail, he helps the head wine bearer, by interpreting his dream. Two years later, Pharaoh has disturbing dreams, and the wine bearer tells him, “There is a young Hebrew slave in jail that knows how to interpret dreams.” Yosef tells Pharaoh that his dreams mean that there will be 7 years of plenty, followed by 7 years of hard famine, and you should plan accordingly. Pharaoh says, “Good idea. You can be in charge.”
Given that the famine was everywhere, and Egypt had plenty of grain to sell, Yaakov sent his sons, minus the youngest, Benjamin, to buy grain from Egypt. The brothers have a feeling that Yosef might be still alive, so they enter through different gates.
Given their strange entry, they were questioned by the person in charge, Yosef.
The Torah mentions that Yosef’s brothers did not recognize him. This is strange given that the commentaries say that he looked VERY much like his father. So you have 10 people looking at a younger version of their dad and not thinking, “Hey! That could be Yosef!”. They even thought that he was still alive, and their experience is eerily similar to the dreams Yosef had when he was younger, so why didn’t they do 1+1+1?
The commentaries say that they couldn’t believe that someone who was a slave could rise up to be the leader. Their disbelief disabled their eyes and ears, and they thought that they were speaking with someone who just happened to look and sound like their father.
Our minds are very powerful, and we can stick to our personal “Truths” even when we see and experience the contrary.