Have you ever seen two things that look the same but they are actually very different? That's kind of like the concept of heterokairy.
In science, heterokairy is when two things that are very similar have different characteristics. For example, plants can have different looking leaves, even though they come from the same plant.
This happens because the plant has two different types of genes that control the way the leaves grow. One gene might make the leaves look long and skinny, while the other gene might make the leaves look short and wide.
So even though the leaves come from the same plant, they look different because of the different genes that control their growth. That's heterokairy in a nutshell!