genetics and disease

Hsien-Hsien Lei of the Eye on DNA blog recently asked readers to define genetics in one simple sentence. I tried, with the following:

Genetics is the study of the operating instructions for life.

To this could be added: Scientists look at how the instructions are passed from one generation to the next, how instructions differ from one living thing to another, and how the instructions work.

For a "young" audience, something modern--operating instructions--could be useful. Note that the second sentence distinguishes the various components of genetic study: inheritance, form, function.