DNA changes in growing organisms

[Matthew]

What evidence is there to support or prove otherwise my thesis that
DNA in living organisms can change minutely from birth to adulthood,
particularly due to learning and/or adaptation to the environment. 

This issue is crucial. What are the difficulties in comparing each and
every gene between samples taken from a young and mature specimen? 

Could software database technology assist in this comparative process.

Who knows more about it?  Please email me, I will thankfully  reply.

Matthew
BioLab at lottery.powernet.co.uk