Inheritance means you "Inherit" certain traits, and that usually comes from the form of genetics, when you are born you inherit traits from your parents, maybe their eye or hair colour, their facial features, or health problems like diabetes, heart disease, or schema.
But if you were to have a sibling, and while your sibling has eczema while you don't, that's a bit strange.
Well, a person named Gregor Mendel, who was a monk in the 19th century, experimented on a simple pea plant.
Now you are probably wondering why did he not experiment on humans, one reason is that it can take decades for humans to be test subjects. As they take years to grow and mature, and can only produce a few children making data collection slow and time-consuming. A plant can have thousands of offspring has a faster growth rate, and matures much quicker.
And also it is a matter of ethics, where it's not really ethical to ask a woman to get pregnant to see what the child looks like compared to the father.
Using Mendel's research scientists and common folk alike can predict certain genes from their parents. Parents before the baby is born will often guess what the baby will look like. Like if the father has brown eyes, or the mother has black hair.
Johann Gregor Mendel born from 1822 - 1884, is commonly referred to as the "Father of genetics", he was a teacher, a scientist, and a man of Christian faith.
Although his education was expensive, he graduated from both high school and university and then joined the Augustine Abbey of St. Thomas in Brno, which is now modern-day the Czech Republic.
He actually went against his father's wishes, instead of focusing on the family farm. He instead went to pursue his education and personal interests, supported by the monastery. He taught: Physics, Botany, and Natural science, at the secondary and university levels.
Then in 1856, he started his decade-long study on patterns of inheritance.
Going from mice to honeybees, to plants and settled on the Pea as his main "primary model system.
A "primary model system" is used when a researcher or scientist wants to study and use an easier specimen, such as the pea plant.
Because studying a pea plant or the model system is much easier compared to humans. By using a model system to learn the basics of inheritance, we are able to form the very basic principles of inheritance and apply them to other organisms like humans.
Mendel created these parameters to measure the differences in parent and child plants: height, flower colour, seed colour, and seed shape.
At first, he was pure-breeding them (using two parent pea plants), then after a few breeding sessions, he noted that the pure-bred plants were nearly identical to the parents, then once the boh parent plants made two children, Mendel would cross-breed the two children.
Mendel would write down the similarities between generations of pea plants and the results were they were extremely similar.
The first generation found that he found the dominant trait was tall, while the recessive trait was short. In the second generation, Mendel allowed the plants to self-pollinate. Then the hidden short trait was revealed. And appeared in the minority of plants, with a 3:1 ratio.
Mendel also found out that a plant can inherit multiple properties independently, as the height of a plant did not intrude on its ability to have different flower colours or seed shapes.
Then in 1865, he presented his findings to the local Natural History Society.
He announced his theory on inheritance with nearly 30,000 pea plants he worked on.
He presented that: There are two types of genes, dominant and recessive, as the dominant would mask the recessive gene,
the paired factors would separate during the gamete (either the sperm or egg) and one gamete would inherit one other factor.
He then made the "Law of segregation", and in 1866 he wrote a book titled "Experiments in Plant Hybridization" in the Proceedings of the Natural History Society of Brünn.
Sadly Mendel's work was unnoticed by his peers for the value they held, and his studies went against what was believed about inheritance, Mendel's approach to biology with a mathematical perspective was seen as taboo.
Then around the 1800s the idea of "Blending inheritance" came about, and the theory that the genes that a child has "blended" genes from their parent since they look similar and similar traits are shared between parents and their children. But this theory did not explain why Mendel, when crossbreeding his pea plants crossbred a tall and short one, and the seeds from that crossbreed were mainly tall peas.
If the blending theory were to be correct, the crossbreed between a tall pea plant, and a short one, was that it would make a medium-height pea plant. But that is not the case.
As Mendel proposed, the plant's height was affected by inheritable factors which were inherited by the offspring of the parents.
But in humans, our height and many other features, inherit fractions of the parent's genes. This makes it exceedingly difficult in certain cases to notice a change affected by the parent's genes. As it is difficult to discern changes in the offspring it can appear to look like blending.
Then in 1868, Mendal at age 42 became an Abbot for his monastery and set his studies aside to work on his pastoral duties. But his work was undervalued and mostly unknown until the year 1900 when his work was found, tested and revitalized.
The pea plant or "Pisum sativum", pea plants was the most convenient for studying gene inheritance and is still used today by geneticists to study inheritance. The key part of why the pea plant was used is that it is a self-fertilizing plant. Meaning it makes both the sperm and egg reproduce and it has the added benefit of producing a lot of seeds in its high-speed life cycle.
Thus Mendel sought to use this fact in practice, he was able to make "true" bred peas and made sure to breed them so that they always follow the parent's genes.
Along with the fact that they are easy to crossbreed, this is done by getting the pollen from the anthers and giving it to a mature pea plant in its carpal of a different variety.
To make sure a plant did not self-pollinate. Mendel painstakingly took out all the anthers on his pea plants.
For Mendel's experiments, he wanted to study their height and how inheritance affected the variances in height. So he set up two generations, one short, one tall.
Then Mendel did a crossbreed between one purebred short and one purebred tall pea plant, and named this generation P.
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