Fortune teller, is it really accurate?

For example, when two middle-aged people go to fortune telling, he calculates that the probability of their having a son is half, and the fortune teller is good at reading people's plates, so his probability of being right is greater than the average. In addition, we usually only hear the propaganda of people who have been accurately calculated, saying that a certain master is very accurate in fortune-telling, but we can't hear anyone talking nonsense about which fortune-teller is, so the more it is spread.

In a word, fortune tellers can really predict many things, but they can't calculate.