Children like to sit while doing things, and since they're learning, they tend to sit in whatever position is easiest and most convenient for them. Recently, people have noticed that one particular position, the go-to position for children, can actually be quite harmful to them in later life. This position is often referred to as the "W" sitting position, as the fanning out of the legs creates a "W."
This position is extremely common for children due to the stability it provides. Since their legs are fanned out, they are given a significant amount of support with the least amount of effort possible. Unfortunately, the "W" position comes with many potential problems. These problems include, but are not limited to, orthopedic problems, delayed development of postural control and stability, and delayed development of refined motor skills.