The term 'genetic pioneer' can be summarized by the name of Gregor Mendel, a 6-letter answer to the crossword. Mendel was an Austrian scientist and Augustinian friar who is often referred to as the 'father of modern genetics'. He conducted experiments with pea plants in the mid-1800s and developed the laws of inheritance, which laid the foundation for the study of genetics. His work was largely unknown until the early 1900s, when his theories were rediscovered and widely accepted.