> Were I to say that the expression of gene A is 'random,' then it would seem to imply that there is some minute chance that the result is a billion copies of t

> Were I to say that the expression of gene A is 'random,' then it would seem to imply that there is some minute chance that the result is a billion copies of the gene Not at all (in mathematical terms, anyway). You can certainly define the probability distribution of a random variable such that only certain values are possible. This is known as its support: https://en.wikipedia.org/wiki/Support_(measure_theory) https://en.wikipedia.org/wiki/Support_(measure_theory)