Guest Author - Alegra M. Bartzat

Reginald Punnett worked with William Bateson at Cambridge doing genetic research. They studied gender determination and gene linkage, following chromosome and gene patterns from parents to offspring. Gene linkage is, more specifically, the inheritance of particular traits that are “tied together” on genes or chromosomes; it is also referred to as coupling.

Though he entered school as a medical student, Punnett received his degree in zoology and studied ribbon worms after college. Later he worked under Bateson and was eventually hired to replace him as a professor at Cambridge University. Punnett followed in the footsteps of Johan Gregor Mendel, studying hereditary traits in plants and animals. He applied mathematical principles to genetics to solve problems that stumped others – such as why the whole world didn’t have brown eyes since brown eyes are dominant.

Punnett is credited with developing the infamous “Punnett square,” used in Genetics 101 classes around the world to determine both simple and complex patterns of dominant and recessive inheritance. This is the square with mother on one side, father on another, and all possible combinations of offspring in the boxes below.


B B
b Bb Bb
b Bb Bb


B b
B BB Bb
b Bb bb


A first generation of, say blue flowering peas and white flowering peas, creates only blue flowering peas. “B” represents blue and “b” represents white. (It’s standard to use one letter for one trait, with capital representing dominant and lowercase representing recessive.)

But when you cross the second generation, which is all blue flowering remember, you get three blue flowering pea plants for every one white flowering pea plant.

This important tool for studying genetics was introduced to the world in Punnett’s book, Mendelism. This book was, if you hadn’t guessed it, based on Gregor Mendel’s research on genetics.

Punnett’s career was successful and he made many discoveries and published many papers that advanced the study of genetics, though none were particularly breakthrough on their own. Punnett maintained an esteemed research career in genetics, earned many honors, was invited to join many exclusive clubs for research, and become editor of the Journal of Genetics after founding the esteemed journal with Bateson in 1910.