Similarity of structures due to common ancestry is called

Similarity of structures due to common ancestry is called homology.

Explanation:

Homology is the relationship that exists between two different organic parts when their genetic determinants have the same evolutionary origin or a common ancestry, that is, it is a feature or characteristic that is shared by all descendants of a common ancestor, and not shared with other groups. For example, the arrangement and structure of limbs in vertebrates are similar, these similarities then come from a common ancestor to all vertebrates.