Acquired traits are structural,functional and behavioural changes that an individual develops during its life time. Due to particular environment trauma use and disuse etc the changes which are acquired do not happen in reproductive cells they just happen in somatic cells . the removal of tails is a acquired trait which is not passed on to DNA of germ cells.They remain restricted to somatic cells. They are destroyed with the death of the mice. Hence the new generation continue to have tails .
Mice tails
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