Canalisation is a big, fancy word that scientists use to describe how much our genes control the way we grow and develop.
Think of your genes like a map that tells your body how to build itself. Sometimes, that map is very specific and tells your body exactly what to do in order to grow and develop properly. Other times, that map is a little bit looser and doesn't give your body as many specific instructions.
Canalisation is all about how strong and specific that map is. If your genes have a really strong influence on your growth and development, we would say that you have a high canalisation. This means that your genes are very good at telling your body what to do, so you grow and develop in a very specific and predictable way.
On the other hand, if your genes are not very good at giving specific instructions, we would say that you have a low canalisation. This means that other factors, like your environment or the things you eat, can have a bigger impact on how you grow and develop.
In general, having a high canalisation is a good thing because it means that your body is more likely to grow and develop in a healthy way. But having a low canalisation can be okay too, because it means that your body is more adaptable and flexible in response to different conditions.