Inherited characteristics
The word this whole chapter turns on is a simple one, and it is worth getting exactly right before anything else is built on it.
Inherited characteristics
Characteristics that are transmitted from generation to generation are called inherited, or hereditary, characteristics.
Two things the definition does not say
Read it carefully. It says nothing about whether the characteristic is useful, and nothing about whether it is visible.
- An inherited characteristic is not necessarily a good one. Some of the disorders later in this chapter are inherited in exactly the same way as eye colour.
- A characteristic can be inherited and not show. That is the discovery Mendel made, and it is the reason a trait can skip a generation and reappear.
Not everything about you is inherited
Plenty of what you look like was not passed to you at all. A scar, a callus, the muscle a year of training builds — none of these came from a parent, and none of them will go to a child. The last page of this skill returns to that distinction, because it is the one people get wrong most often.
Inherited means transmitted, nothing more
Every use of the word in this chapter means one thing: it came from a previous generation and can go to the next. Hold the definition that tightly and the disorders later on stop being a separate topic.
The test is where it came from
A characteristic is inherited if it is transmitted from one generation to the next. Whether it is visible, useful or welcome has nothing to do with it.