It's in My Genes by Michel

A masterpiece of stand-up magic! 

The magician says, "To learn magic you have to study. But I wonder if it has something to do with heredity. My son is 5 years old and he's a gifted child." 

The magician asks a spectator to come on stage. Assume, in this example, that his name is Tom. A plastic, yellow envelope with a big label is shown, with words printed on it: "Choose a Number from 1 to 100." The magician asks Tom to point to anyone in the audience and asks him to choose any number. It is written on a Post-it note and sticks it on Tom's right palm. 

The yellow envelope is opened, and a smaller plastic grey envelope is removed. It has a big printed label that says, "Choose a letter." The magician asks Tom to point to another spectator in the audience to choose any letter. After he calls it aloud, it is written on a Post-it note and stuck onto Tom's chest. 

The envelope is opened and a box of jumbo cards with different printed flags on the faces is removed. Another spectator selects, in a crystal-clear way, one of the "flag cards." Tom holds the "flag card" in his left hand. The spectator who chose the "flag card" looks into the box and he finds an envelope with child drawings. The magician says, "Today my son arrived from school and gave me this envelope." Inside, there's a drawing of Tom with the same number held in his hand, the same letter on his chest and the same "flag card" in his hand. Everything matches!