It is important to understand the instinct of The Genes. For example, a child with loving grandparents has better chances of survival. Extrapolate into the future, such grandchild with similar disposition towards grandchildren will enhance the survival of his descendants. Conclusion, genes that love grandchildren survive. It explains why brothers love each other when they are young and fight each other when they are old to claim assets for their children and grandchildren.
Nature encourages such behavior, blame it on the genes.
When choosing a wife, friend or business partner, look for a person who has integrity, is hardworking and intelligent. One way is to see how he behaves towards his parents, his siblings, his friends, his subordinates. Know where the brown and green wires go in a plug. Know how the electric motor works, what goes on in a piston engine and why clothes dry in a centrifugal dryer. Do not bully others and do not allow others to bully you.