A trait is any describable characteristic of an individual: eye color, blood group, earlobe shape, height, a singing voice, a scar. The individual’s whole collection of traits is built by two workings: what was inherited, and what the environment and life added (Definition 28.1’s world, acting on one body).
Examples
Example 63.5 (Traits that skip)
Some patterns puzzle at first sight: two brown-eyed parents with a blue-eyed child; grandmother’s trait absent in every child yet returning in a grandchild. Skipping is common, and it carries a heavy conclusion: a parent can transmit what they do not show. The trait’s instructions traveled hidden through a generation — so what is inherited is not the trait itself but something that determines it, carriable unseen.