Human hair is one of material used to identify heredity of an individual. There has been a lot of researches done by scientists in sophisticated ways to test inheritance based on hair characteristics. However, to teach this uniqueness at the school level can be done with a simple test. One of them with natural grating method. This study aims to analyze the interference patterns produced by hair from the diffraction process. Five non-blood related families were examined. A beam of 800 nm wavelength from the laser is passed through the hair and its lattice width is calculated. Lattice gap data obtained are then calculated the correlation value between mother and child father. The results of this simple analysis are not enough to support the inheritance relationship of one family. Obtained mystery figures that still need to be studied further. But found one family with twins who have the same width of hair gap. This finding is certainly very interesting to be taught to students at the school level.