Gregor Mendel, an Austrian monk, conducted early experiments in genetics and inheritance through breeding pea plants. Over 10 years, he tracked traits like seed color, flower color, and pod shape across 28,000 pea plants. His large, replicated experiments helped establish the basic principles of genetics, including that traits are determined by discrete inherited factors (now called genes), offspring inherit one factor from each parent, and traits can be passed on even if not expressed.