Johann Mendel, later known as Gregor Mendel, was born on July 22, 1822, in Heinzendorf bei Odrau, a little village in a part of the Austrian Empire known today as the Czech Republic, or more recently, Czechia.

Mendel is considered the father of modern genetics, but his work was largely ignored until after his death in ­­1884.

He assumed the added name of Gregor upon joining a monastery in 1843, where he tended the monks' gardens and conducted his well-known pea plant experiments.

Johann Mendel was born to peasant farmers, Anton and Rosine Mendel. He grew up in a German-speaking rural area with his parents and two sisters, Veronika and Theresia. Johann attended a prep school called a Gymnasium where his academic promise was recognized by the local priest. At age 11, he was sent away to a school in Troppau.

Being of humble means, his family could not support the boy once he left home. Mendel had to tutor other students to support himself. Throughout his education, he suffered from bouts of depression and returned home periodically to recover, but eventually he graduated.

Mendel then entered a two-year program at the Philosophical Institute of the University of Olmütz, also called Olomouc; this program was required before starting university studies.

Things did not go so well for Mendel in Olomouc, despite his intelligence and love of learning. He experienced more financial difficulties given the language barrier he faced in the primarily Czech-speaking region.

Once again he experienced severe depression and had to return home to recover.

His younger sister, Theresia, encouraged her brother to finish his education, and even offered to help him with the cost of his schooling. Theresia generously gave Johann her portion of the family estate that she had been planning to use has a dowry.

Years later, Mendel repaid the debt by helping her raise her three sons. Two of them became physicians.

Young Mendel wanted to further his education but could not afford to do so. A professor urged him to join the Abbey of St. Thomas monastery in Brünn (Brno, Czech Republic) and continue his education. Mendel’s inquisitive and analytical mind drew him to the study of math and science. He chose St. Thomas because of the ­­­order’s reputation for progressive thinking inspired by the Age of the Enlightenment.

The monastery operated under the Augustinian credo per scientiam ad sapientiam ("from knowledge to wisdom") and focused on scholarly teaching and research. Upon entering the monastery as a novice in 1843 his name became Gregor Johann Mendel.

His formal schooling and personal experience growing up on a farm made him an asset to the order’s agricultural operations.

The Moravian Catholic Church, along with intellectuals and aristocrats, were becoming aware of the importance of science in the 1900s. Gregor Mendel was urged to learn all types of sciences, including plant cultivation. In stark contrast to the rest of his life, Mendel enjoyed the luxury of fine dining.

The monastery was renowned for gastronomy and culinary arts instruction.

Gregor Mendel attended classes at the Brünn Theological College and in 1847, he was ordained a priest. As part of his monastic duties, he worked as a high-school level science teacher. However, he failed a new teacher certification exam in 1850 and examiners recommended that he attend college for two years before taking the test again.

Between 1851-1853, Gregor Mendel enjoyed studying at the University of Vienna under the tutelage of renowned mathematicians and physicists Christian Doppler and Andreas von Ettinghausen. Mendel deepened his understanding of plants when working with botanist Franz Unger.

Mendel’s dissertation explored the origin of rocks, which was a controversial topic at that time.

At the University of Vienna, Mendel learned advanced research technique and scientific methodologies, which he later applied to the systematic cultivation of pea plants. He is called the father of modern genetics because he identified the fundamentals laws of inheritance and calculated their statistical probabilities, a skill that he honed at UV.

Mendel was one of the first scientists to incorporate mathematics into the field of biology.

Gregor Mendel spent several years of his career teaching high school students at schools in and around Brünn while he resided at St. Thomas monastery. The young monk obtained permission from his superiors to conduct a longitudinal study of plant hybridization in his free time. Mendel was allowed to perform experiments in his own laboratory, which was essentially the monastery greenhouse and 5-acre garden plot.

Later in life, Mendel became abbot of St. Thomas monastery where he lived and worked for the remainder of his days on Earth.

Mendel’s first genetic experiment started with mice, and then he moved on to garden peas (genus Pisum). Mendel’s work with mice came to a halt when the bishop learned that Mendel was raising caged mice in his small living quarters. If Mendel had gotten around to crossing pure breeding black and white mice, he would have made an interesting discovery related to codominance and incomplete dominance.

Mendelian genetics – grounded in observations of inherited garden pea traits – would have erroneously predicted all black mice, not gray mice, in the first generation (F₁).

Mendel began to plan programs in experimental hybridization of peas at the monastery in 1854. His work was welcomed by abbot Cyril Knapp, who considered the study of traits relevant to international trade that was jeopardizing the monastery’s finances. The monks raised sheep and were concerned about Australian wool imports encroaching on their Merino wool profit margin.

Mendel chose to study garden-variety peas instead of sheep because peas are easy to grow and come in many varieties, and pollination can be controlled.

Between 1854 to 1856 Mendel cultivated and tested 28,000 to 29,000 pea plants. He used statistical models of probability when analyzing the transmission of observable traits. His exhaustive study included tests of 34 varieties of garden peas for trait consistency over several generations.

Mendel’s methodology consisted of crossing varieties of purebred (true breeding) pea plants, and planting the seeds to learn how traits are inherited in the first generation (F₁). Mendel recorded stem height, flower color, flower position on the stem, seed shape, pod shape, seed color and pod color. He noted that inherited “factors” (identified as alleles and genes today) were either dominant or recessive for certain traits.

When seeds from cross-pollinated F₁ plants grew, they produced a three-to-one ratio of dominant to recessive traits in the next generation (F₂).

Mendel’s findings were not consistent with the ideas of the time, including those of the famous evolutionary biologist Charles Darwin. Like most 19th-century scientists, Darwin thought traits blended, such as a red flower pollinating with a white flower producing pink flowers. Although Darwin noted a a three-to-one ratio of dominant and recessive traits in snapdragons, he didn’t understand the significance.

Statistician Ronald Fisher opined that Mendel’s data and statistical calculations were too perfect to be believable. Other scientists jumped into the fray alleging that research errors, along with Mendel’s conscious or unconscious bias, skewed results. For example, judging phenotypes such as whether a pea is round or wrinkled involves subjectivity.

However, defenders of Mendel’s legacy replicated experiments, ran their own calculations of statistical probability and concluded that Mendel’s findings were valid.

In the 1900s, Mendel posthumously rose from obscurity to fame when Carl Correns, Hugo de Vries and Erich Tschermak independently published research findings consistent with Mendel’s results.

The extent to which any of the scientists were familiar with Mendel’s prior hybridization experiments is disputed. The studies corroborated Mendel’s discovery of dominant and recessive traits.

In addition to being a priest, teacher, gardener and researcher, Mendel was a scholarly writer and lecturer. He published papers describing crop damage by insects.

Mendel also gave lectures on his work at two meetings of the Natural History Society of Brünn in Moravia in 1865. He published his work, "Experiments in Plant Hybridization" in 1866 in Proceedings of the Natural History Society of Brünn.

Mendel’s research in a vegetable garden led to Mendel’s theory of heredity and two main findings: the law of segregation and the law of independent assortment.

According to the law of segregation, a pair of hereditary “factors” (alleles) for a given trait separate when haploid eggs and sperm cells form. A fertilized egg has two copies of each allele; one copy inherited from the mother and one copy from the father.

The law of independent assortment states that segregation of an allele pair is generally independent of the actions of other genes, with the exception of linked genes.

Mendel’s insights into the laws of inheritance had little impact initially and were cited about three times over the next 35 years. Mendel died before his contributions to genetics were understood.

The discovery of the deoxyribonucleic acid (DNA) molecule at King's College in London led to advances in genetics, medicine and biotechnology. Geneticists were finally able to identify the vaguely understood hereditary "factors" inferred by Mendel.

Gregor Mendel's principles of genetics apply to characteristics controlled by a dominant or recessive gene. In the case of pea plants, each of the investigated traits like stem height was determined by one gene with two potential alleles.

Inherited pairs of alleles were either dominant or recessive, and no blending occurred. For instance, the crossing of a tall stem plant with a short stem plant didn’t result in a plant stem of average height.

Non-Mendelian genetics explain more complicated patterns of inheritance. Codominance occurs when both alleles exert their influence. Incomplete dominance happens when the dominant trait is slightly muted, such as pink instead of red coloring. Many types of alleles may be possible for a given trait.

Mendel was promoted to abbot in 1868 and took over the administration of the monastery. He focused on these duties after this point and did not continue experimentation. Acquired data sat on a shelf, and his hand-written notes were burnt by his predecessor.

Mendel died of Bright disease, also known as nephritis, on January 6, 1884. He was remembered as a Catholic priest with a passion for gardening. Even those who admired his intellect and scientific rigor did not realize that their friend and colleague would become legendary in the distant future.

Mendel’s experiments were motivated by his love of science. No one other than Mendel had an inkling that his work was groundbreaking. Despite his bouts with depression, Mendel remained optimistic that his contributions to science would one day be recognized. He often shared such thoughts with friends:

"My scientific studies have afforded me great gratification; and I am convinced that it will not be long before the whole world acknowledges the results of my work.”

“Even though I have experienced some dark hours during my life time, I am grateful that the beautiful hours have outweighed the dark ones by far.”