A Tale of Two Mice A mouse gives birth to identical-twin sisters. One has brown fur and will grow up to be lean and healthy; the other has yellow fur and is destined to be obese and prone to disease.

Harvard . 2006. Genetic Mutation in Mice Suggests Extinct Mammoth Had Light and Dark Fur.

The mice on the left-hand side have active AVY genes, giving them golden fur, while those on the right have silenced AVY genes A mother's diet can change the behaviour of a specific gene for at ...