Why do some genetic traits skip a generation?

In classical genetics, a recessive trait appears only when a person inherits two copies of the relevant variant, one from each parent. If someone has just one copy, they may be a carrier without showing the trait themselves. Polygenic traits can also look as if they skip generations because many genes and environmental factors combine to produce them. This is common in family traits such as some forms of eye color, disease risk, and pigmentation patterns.