I am not a very good sleeper. Going to bed upset or overwhelmed can keep me up and tossing until 3 a.m. You might think, then, that I would welcome the imperative that one should resolve all disagreements before settling down for the night. Should I perhaps be heeding the wisdom in the New Testament verse — “Let not the sun go down upon your wrath” (Ephesians 4:26) — often quoted as the source for this entrenched belief?
First the bad news: Sibling rivalry can not be eliminated entirely. Children are sensitive to differences in parental treatment from a young age, possibly even from the age of one year (Judy Dunn). By 3 years old, children already have a sophisticated grasp of social rules, can evaluate themselves in relation to their siblings, and know how to adapt to circumstances within the family.