Stammering is not caused by any physical defect, nor is it simply the result of fear or nervousness — This is a common misconception, as even fluent speakers may stammer under pressure. Stammering primarily develops due to specific neurological conditions development over the period of time, often reinforced by childhood habits that persist into adulthood. It becomes default setting of your body.

It starts at an early age due to various reasons like :

1. Neurophysiological Factors : In newborn babies, fine-tuning of the speech mechanism, language development occurs during the early years, involving processes like auditory-motor integration, timing and motor coordination, brain activation patterns and how the brain processes language. Speech development depends on multiple complex permutations and combinations of these systems. If any disruption occurs during this critical period, it can lead to specific neurodevelopmental conditions. Stammering is indeed common in early childhood, typically appearing between ages 2 and 6.and about 75% recover naturally, while a small percentage continue to experience it into adulthood. When stammering continues past childhood, it often becomes a lasting neurodevelopmental condition and part of a person’s natural way of speaking.
2. Psychological and Physical Factors : In some cases, psychological trauma, bad environment or even rare cases of physical injuries, such as accidents, strokes, or surgeries affecting speech-related areas of the brain. Psychological factors contribute to the development of specific personality traits which can ultimately influence neurodevelopmental states that persist throughout a person’s lifetime.
3. Speech and Language Development Delays : Children who start speaking later or have delays in speech and language skills may be more prone to stammering.
4. Imitation or Learned Behaviour : A child might pick up stammering-like patterns from someone they spend a lot of time with (e.g., a parent, sibling, or close friend who stammers).

This all ultimately leads to specific habit formation, which contributes to the development of certain neurological conditions, I call it as default setting of speech mechanism. As a result, a person continues with that neurological condition throughout their lifetime and we all are calling it as stammering OR stuttering.

The speech mechanism is not just about the coordination between the brain and speech organs. It also involves multiple internal systems. These elements work together automatically, forming a person’s default speech mechanism, which develops without conscious efforts.

That’s the reason why stammering person not faced this issue during singing, mimicry and talking with different accent or talking with pets/children’s because person is intentionally not talking with his default speech mechanism. During these activities he is articulating his default way of speaking.