What causes the stubborn behavior in 3 year old?

Stubborn behavior in 3-year-olds often stems from their developing sense of autonomy and desire for independence. At this age, children are learning to assert themselves and test boundaries, which can manifest as defiance or refusal to comply with requests. Additionally, they may struggle with emotional regulation and communication, leading to frustration when they cannot express their needs or desires effectively. This behavior is a normal part of their growth and development.