- Created: Tuesday, 13 November 2012 00:00
- Written by Nadia O’Carroll
It is amazing to think that billions of living organisms on Earth are discrete individuals. Even organisms which are genetically identical to their parents and siblings change over time due to environmental factors and mutations to produce tiny differences which make them unique.
For many species, sexual reproduction where the male and female parent each contribute fifty percent of molecular DNA, ensure that the offspring are genetically different from their parents and their siblings. There are exceptions where siblings have the same DNA; the most familiar is identical twins. This occurs when one fertilised egg splits into two cells. Identical twins are genetic duplicates, but even before birth they begin to develop individually and by the time they are born they have different fingerprints and are no longer exact replicas of each other. Over time environmental factors and slight physical changes and mutations cause increasing divergence between twins.