Genes and Environment: Traits Come from Both

0:00Do your genes alone decide every one of your traits?

0:04A trait is a feature of a living thing that you can observe or measure.

0:09Genes are sections of DNA that carry the code for making proteins.

0:15The environment means the conditions around an organism, such as temperature, soil and food.

0:22Many traits are shaped by genes and the environment working together.

0:27Look at a Siamese cat. Its face, ears, paws and tail are dark, but its body is pale.

0:35Its genes code for an enzyme, a protein that helps make dark pigment. This enzyme works only below normal body temperature.

0:44These parts are cooler than the rest of the body, so only they grow dark fur.

0:49Now take two hydrangea plants with the same genes.

0:53In acidic soil they flower blue, but in alkaline soil they flower pink.

1:01Identical twins come from one fertilized egg, so they share the same genes.

1:07Height depends on genes and on food. A twin who gets too little food while growing may end up shorter.

1:15So identical twins can still differ, because their environments are not exactly the same.

1:22So the idea that genes alone decide every trait is a misconception.

1:28Some traits, like blood group, are set by genes alone, but many others depend on both.

1:34Many traits come from both genes and the environment, not from genes alone.