¿Why do people give their opinions without knowing?

So, the other day I went out with my father, then the traffic light turned red and a friendly and pretty lady dressed as a clown came out. she was asking for support, she asks for money. When the light turned green we moved forward and my father saw two children playing on the street where the lady dressed as a clown was. He told me: "that lady is a teenager and already has two children."And my question is, how can you be sure that they are your children and not your brothers or cousins? In my point of view we should not inform ourselves well before speaking We only know ten percent of the problem, when the problem is ninety percent.