Answer: stereotype
Step-by-step explanation:
Stereotypes are preconceived ideas and beliefs that we have about a certain group of people which in may cases is based on being judgemental or based on prejudice, these are the beliefs that we conclude in our mind from a distance without truly testing them in real life.
Terry had a stereotype that if people have many kids they probably are selfish and irresponsible until he met his neighbour who showed something opposite to Terry's false beliefs by being a responsible and generous parent despite having many kids.