Question

Why do identical twins become increasingly different over time?

Answer 1

Explanation:

Identical twins may have less in common than they think. A study now shows that the expression of their genes gets more and more different with age.

The findings could help to explain why one twin may develop a genetically influenced disease, such as diabetes, while the other remains perfectly healthy.

Identical twins have identical genes, because they are born of an embryo that splits at a very early stage in development. Such twins are often indistinguishable in outward appearance. But over the course of time they may experience radically dissimilar health.

Most scientists have assumed that environmental and lifestyle differences cause such divergence. These things trigger chemical reactions that affect our DNA and the proteins entwined with our DNA, called histones. One such reaction, known as methylation, influences the expression of genes and so can have an impact on health.