From the color of Your Eyes to Your Type of Earwax


If the last thing you learned about genes was Gregor Mendel’s pea pod experiments, you might want to try this easy to read science book to get up to speed about many fascinating changes in hereditary theory.

For instance, humans have only 20,000 to 25,000 genes, downgraded from a previous estimate of 100,000.  In comparison, a tiny water flea--barely visible to our naked eye--has about 31,000.

You’ve heard the word genome in the news and on PBS. Your genome is your full set of genes. Every cell in your body gets a copy of the full set although each cell cannot read all of them.  By the way, the word “cell” came from Robert Hooke, the first person who saw them in the 1600s. When he first discovered them under a microscope, they reminded him of monks’ cells.

Other interesting facts about your genome.  The chromosomes scientists have discovered have something to do with either inherited diseases or traits. For instance, chromosome 1 is associated with deafness, schizophrenia and maple syrup disease.  (You read that right!) If you have red hair, thank chromosome 2.  Blue or green eyes?  Chromosome 19 is for you.  And yes, previously scientists thought that there were only two possibilities for eye color: brown or blue.  Those green eyes, they just tagged as a variant of blue.

On the other hand, there are only two possible kinds of earwax, dry or wet.  And if you have the wet variety, you are more likely to suffer from body odor from more bacteria on the skin. Also, this kind of trait that is controlled by one gene with only 2 or 3 possible outcomes is called a Mendelian one. Other examples of Mendelian traits are attached or free earlobes, having a widow’s peak or not, and hairy or smooth knuckles. Now you have something to blame!

McKissick even lists how to conduct an experiment to discover whether you have few, average, or a super amount of taste buds. All that you need to check out your tongue is blue food dye, a reinforcement tab for a hole-punch (to size the area), and a cotton swab.

The author covers many other compelling subjects: the thirteen year long history of the Human Genome Project, the genomes of twins, how nurture affects what you are born with and the future of genetics itself. Reassuringly, McKissick tells us newborns won’t come with a print-out of their chromosomes and what diseases they might eventually get anytime soon or hopefully anytime. She does, however, encourage the reader to have his or her DNA sequenced. This can help scientists with their work in identifying diseases early and developing cures and to continue learning about how genes work.

For a more academic approach of heredity, try In Pursuit of the Gene by James Schwartz. It covers the history of scientific discovery regarding genes from Darwin through the first decade of this century.