The main sources of beliefs are education, personal experience, social stereotypes, and authorities.
Our parents, our parents' parents, etc., received some specific experience, on the basis of this experience, a belief was born and in the process of education it was passed on to us, and we accepted it as our own. Such beliefs received in childhood, people are not inclined to check later and protect as "their", "native".
For example, the father told his son that crying in front of people shows your weakness, the son took it and now he is raising his son in the same way.
What people say and what they write in Newspapers, popular points of view today, replicated orally and in writing - a powerful source of influence. However, they are effective primarily when a person does not have a point of view on this issue. If the position is already developed, beliefs are formed, then the social stereotypes that contradict them act as "different" and often only strengthen the beliefs that already exist.
If the culture began to spread women's attitudes "Suppressing emotions can be harmful", "Men can cry", they only cause a smile in those who were brought up as a man and are familiar with serious research in experimental psychology.
There's a big problem with personal experience. The subjectivity of human perception is such that people can easily, based on their personal experience, successfully convince themselves of what they were previously sure of.
Those who are convinced that it is harmful to suppress emotions find confirmation of their point of view. Those who know that the control of emotions is a natural thing and simply mandatory, based on their experience, are daily convinced of their rightness.
Personal experience of an unbalanced person based on random emotional impressions is a source of everyday superstitions.
Imagine that you are in love for the first time, and you are filled with the desire to share with your loved one your innermost thoughts and feelings, you want to give everything to your loved one. And you don't hesitate to share it all. And your young man or girl in a private conversation with friends voices these your innermost thoughts. This behavior of a loved one is easy to assess as a betrayal, experience heartache and make a decision: you can not be open with anyone, they can betray. This is a bad decision, but many people live with it for years.
The personal experience of a reasonable person, based on a sufficient series of observations and experimental tests, deserves more respect.
Authorities are strong and important, the only problem is that there are no generally recognized authorities or few. Science is not an authority for everyone, and religious authorities also do not fully agree with each other.
Nevertheless, it is authority and personal experience that are the most respected sources of belief for wise people.