Student or Learner
What does this sentence means actually? "Smaller families are not necessarily less interesting than big ones."
Does it mean that smaller families are more interesting than big ones?
No. It means that it's not necessarily true that small families are less interesting than big ones. This does not make any judgement about whether big or small families are more interesting. In fact, it says specifically that small families cannot be judged to be less interesting. Nor can it be said that big families are more interesting.