1.
atavism; throwback; skipping a generation
A genetic phenomenon where a trait from a grandparent or earlier ancestor reappears in a descendant, having skipped one or more intervening generations. Also used colloquially to describe personality traits or talents that seem inherited from grandparents.
Usage
隔世 means "separated by a generation" and 遺伝 means "heredity/genetics." While technically a scientific term, it is commonly used in everyday conversation when noticing traits that seem to have skipped a generation.
In strict genetics, atavism refers to the reappearance of ancestral traits due to recessive gene expression. In everyday Japanese, the term is used more loosely to describe any perceived similarity to grandparents.