Affinity.

About Affinity

Affinity (taxonomy) – mainly in life sciences or natural history – refers to resemblance suggesting a common descent, phylogenetic relationship, or type. The term does, however, have broader application, such as in geology (for example, in descriptive and theoretical works), and similarly in astronomy (for example, see "Centaur object" in the context of 2060 Chiron's close affinity with icy comet nuclei.)