Most siblings know they love each other but rarely express it as children. I think children need to be taught to appreciate other people just as they need to be taught their ABC's and how to tie their shoes. They need to learn gratitude for having people in their lives who love and care about them. This is one way to get children to be less ME focused and more focused on others.
Every night at dinner we pick one person in the family and each of us tells them something we appreciate or love about them. It has really helped our children be more loving to each other and realize that it is a precious gift to have a family. It is also super simple and fun! Every dinner time they ask who's turn it is to be complimented. And don't forget parents too!