The first teeth you get immediately after birth just like you get your first opinions from your parents and social environment. Later in life you develop your own opinions just like you lose your original teeth (called milk teeth) and develop more permanent ones that are probably gonna last you a lifetime.
If you do not occasionally change your views on things even later in life based on new information, then you’re not doing very much thinking. Your thought is incomplete, we should have more than two sets of opinions.