Chinese - Redundant Words

My son is learning Mandarin at school. Some of the first words that he's learnt relate to numbers and family members. It's interesting that the Chinese have words for sister, brother, older sister, younger sister, older brother, younger brother, etc. Aren't these words somewhat redundant, or about to become so, due to the one child policy? Did the Communist fathers consider this issue when implementing this policy? An unfortunate by-product methinks.