Are sizes of potatoes normally distributed?
According to Evaluation of the Effect of Density on Potato Yield and Tuber Size Distribution potato tuber size was estimated using a normal distribution but they are not normally distributed
They found that a Weibull distribution with specific parameters estimated better than a normal distribution.
In fact you should not expect a normal distribution because there are no potatoes of negative size  As such you expect a gamma distribution.  The Weibull distribution is in the same family of distributions.
But in many cases the normal distribution is used since the probability of a negative number is negligigble.
Does this mean that potato sizes are still the result of many factors? It would seem so