Molecular Biology Review

A study was recently conducted on what makes twins different. Some identical twins have small physical difference or tend to be more susceptible to disease than their pair. The theory for why these differences occur, as addressed in this article, is that chemical triggers switch on and off genes. They do this by attaching to the chromosome “like charms on a charm bracelet”. This is called epigenetic modification. These chemicals come from virtual all around us in the environment. They affect genes differently depending on the chemical. Methyl groups, for instance, turn genes off where as acetyl groups turn genes on.

The study conducted examined 80 pairs of twins from three countries in Europe, who varied between the ages of 3-74. The study revealed fewer epigenetic differences in younger twins. Older twins and twins raised apart presented more differences. The conclusion of the study was that environmental changes such as whether