When to expect normal distribution?

Question

I was wondering when a normal distribution can be expected. I know that things like:

1. heights of people
2. size of things produced by machines
3. errors in measurements
4. blood pressure
5. marks on a test
   
   (source: Math is Fun)

follow a normal distribution. But would for example the chosen nicknames of people also fall in that category? And if so or if not, why would that be?

Answer 1

Basically, the accumulation of a large number of very small independent contributions will be approximately normal (according to the Central Limit Theorem). For example, take heights of people: if you're talking about a homogeneous population, all adults of the same gender, so that the height differences are the result only of small environmental and genetic differences, the normal distribution might be a good approximation. But if you have males and females, that's a single factor that makes a significant difference (typically around 13 cm), and the deviation from normal distribution will be noticeable. It would be even more noticeable if you had a population consisting of Dutch men and Indonesian women.