Identical twins possess exactly the same set of genes. Yet as
they grow older, they may begin to display subtle differences.
They may start to look different, develop different diseases or
slide into different persons.
1. ______. Women who
are identical twins may differ with their fertility or
2. ______. the
age at which they reach menopause. These discrepancies usually
attributed to ill-defined differences in environment.
3.
______. But a whole new level of explanation has been opened up
by a generic survey
4. ______.
showing that identical twins, because they grow older, differ increasingly
in
5. ______. what is known as their
epigenome. The term refers to natural chemical modifications
that occur in a person’s genome shortly before
6. ______. conception and that act on
a gene as a gas pedal or a brake, marking it for higher or lower activity.
7. ______. Identical twins have the same set
of epigenetic mark on the genome
8. ______. when they are born. But
differences in the epigenome disappear
9. ______. as the twins
grow older and become greater the longer they live together,
10. ______. say a team of researchers
led by Dr. Manel Esteller of the Spanish National Cancer Center in Madrid.