Affection is used to denote a feeling or type of love, amounting to more than goodwill or friendship.. Sisters are the pillar of strength in difficult situations. One of the most understated of relationships, perhaps, is the one that sisters share-it's one of the strongest bonds any girl can have. And a new study confirms that having a sister is not just about hair-pulling or tiffs over clothes. Having a sister means having a bond that truly can never be broken.....