How do Jonas and his parents differ in their understanding of love in "The Giver"?
Because the Giver has given Jonas the memory, he understands the "warmth and happiness" of people joined together in love. He watches a scene of a multigenerational family celebrating Christmas, basking together in the excitement and delight that comes with sharing the gifts and camaraderie of the holiday. When Jonas sees "a small child...(sitting) on the lap of (an) old woman, (who) rock(s) him and rub(s) her cheek agains his", he is momentarity confused, because in his society the old are segregated from the young, and family units are temporary. Even so, Jonas recognizes the closeness the family shares, and "luxuriates in the warm and comforting memory...it had all been there, all the things he had learned to treasure".
Jonas's parents have a very different understanding of love. Having lived exclusively in the society where close, lasting relationships have been sacrificed in the interest of order and "sameness", they have no concept of the deep emotions Jonas has experienced. When Jonas asks if they love him, his parents are bemused, and actually chide him for not using "preciseness of language". Love, to them, is "a very generalized word, so meaningless that it's become almost obsolete". They can say they "enjoy" Jonas, and "take pride in (his) accomplishments", but the idea of a deep, abiding love is beyond their understanding (Chapter 16).