Question

Why is genetic drift more likely to occur in a population with few members?

Answer 1

Answer
A favorable variation in a large population is likely to be swallowed up to the point of having little impact on a large population. There are a number of possible variations in the genetic makeup of most populations. These variations are preserved in the population.
For example, skin color in humans is controlled by at least seven different genes. There is a random sorting of these genetic factors. Some people within the same family have a variety of skin colors. Interbreeding will cause these variations to average out in a large population