3. Branch of Biology that deals the study of genes and heredity (dictionary.com)
4. The study of the patterns of inheritance of specific traits. Relating to genes and genetic information. Modern theories explain how traits are passed down from parent to offspring. (biology-online.org)
Supplement: The first to test this theory was Gregor Mendel, a monk from Austria who tried to explain why some pea plants were short and some were tall, but none were in between. He placed nets over the plants so no bees or flies could pollinate the plants.
Pea plants are one of the few plants capable of self pollination, so Mendel tried this with short plants and all were short, so he expected that the same thing would happen with the tall plants. But when he tried it, 75% were tall and 25% were short. This was when he used a Punnett Square. A Punnett Square is a model used to predict the possible outcomes of offspring. (biology-online.org)
Word origin: From Ancient Greek γενετικός genetikos, “genitive” and that from γένεσις genesis, “origin”