What are the differences between voluntary and biological families?

Biological families are related by blood. Voluntary families it means a non-biological parents is a legal parent to a child.

Explanation:

The father and mother whose DNA a child carries are usually called the child’s biological parents. Legal parents have a family relationship to the child by law, but do not need to be related by blood

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explanation:

because i the point in view is between characters

i think it's either 'to expose the corruption of the communists in russia', or 'to criticize animal brutality by communists in russia.'  

hope this ! : )