As you guess, the use of the definite article with nouns that carry some kind of emotional attachment (like child or mother) sounds a little impersonal. Actually this is the intended nuance. The definite article removes the emotional attachment, allowing the speaker to talk as an unaffected observer:
During the brief war, the father of the family left to fight with the partisans. They never saw him again.
Of course, it's not always this dramatic, and as the reader you may still feel some kind of emotional response, in the appropriate context.
This kind of thing is common in scientific writing where "the subjects" of the study are meant to be observed and measured impartially and objectively. In this context there is no negative connotation of "the mother" or "the child". It's merely a statement that expresses certain facts.