article_snippet.sent: Environmental factors alter the methylation status of DNA, changing the way it works.
article_snippet.sent: For example, if one twin has a job outdoors and the other a desk job, the methylation profile will be slightly different.
article_snippet.sent: Crucially, methylation changes the number of hydrogen bonds.
article_snippet.sent: Dr Williams said: ‘Consequently, if one DNA sequence is more methylated than the other, then the melting temperatures of the two samples will differ - a difference that can be measured, and which will establish the difference between two identical twins.
article_snippet.sent: For example young twins, or twins raised in highly similar environments, may not have yet developed sufficient methylation differences.