These purple-flowered plants are not just pretty to look at. Plants like these led to a huge leap forward in biology. The plants are common garden peas, and they were studied in the mid-1800s by an Austrian monk named Gregor Mendel. With his careful experiments, Mendel uncovered the secrets of heredity, or how parents pass characteristics to their offspring. You may not care much about heredity in pea plants, but you probably care about your own heredity. Mendel’s discoveries apply to you as well as to peas—and to all other living things that reproduce sexually. In this chapter, you will read about Mendel’s experiments and the secrets of heredity that he discovered.