Heredity and genes

Is it Leon? My Goodness, how you have grown! And a chip off the old block! Look, exactly your father's chin! Hello!

Lovely to see you! Yes, your chin looks pretty much like your father's, doesn't it? And grandma's too, perhaps? Most people look like their parents. And the same goes for all living creatures.

Two white furry dogs get white furry puppies - not small, spotted puppies. And they certainly don't get kittens. From a strawberry plant you can get more strawberry plants. But no raspberry plants, nor apple trees. We look like our relatives, because we inherit many characteristics from our parents and ancestors.

This applies both to appearance and to other traits, like... being good at music or running fast. Humans noticed this early. Several thousand years ago, people tried putting animals - with various useful traits - together to mate. When a good hunting dog mated with another good hunting dog, chances were high that the result would be an even better hunting dog.

This is breeding. People bred their animals to develop different breeds with different characteristics. Some dog breeds became aggressive guard dogs, others became good at tracking, or pulling sleds. The first to study how traits are inherited scientifically was this man. My name is Gregor Mendel.

I am a monk and a scientist. Mendel lived in the 19th Century, and he is mostly known for his experiments with pea flowers. It's estimated that he grew about 30,000 plants! Mendel figured out a pattern for how the plants inherited their characteristics. He observed that if a plant with purple flowers was mixed with a plant with white flowers... -- the new plants got purple flowers.

But if he interbred the new purple coloured plants... -- the white colour showed up again. A quarter of the offspring became white flowered. So the flower did not get a colour in between, they didn't become light purple, or pink. Gregor Mendel drew some conclusions. He understood that a plant can carry the predisposition - or trait - for two colours at the same time.

But both traits don't have to be visible. Some traits are present in the flower, and can be passed on to the next generation without affecting the plant's outer appearance. Mendel carried out the first experiments in the theory of heredity. A theory which opened a door to a new area of study that quickly changed our perspective on the science of Biology, and the evolution of life... -- and taught us why we inherit characteristics from our parents.