Gregor Mendel was an Austrian monk who studied inheritance through experiments with pea plants in the mid-1800s. He discovered that genes are passed from parents to offspring and that some genes are dominant and will show up in offspring while others are recessive and may not. He also found that alleles separate independently during gamete formation. His work helped establish the basic principles of genetics including phenotypes, genotypes, Punnett squares, incomplete dominance, codominance, polygenic traits, meiosis, and linked genes.