In a family of two or more children, each child has a stronger affinity for a different parent. There are two main ways this can happen:
Each child resembles a different parent in looks or personality.
Each parent is closer to or favours a different child.
These tend to go hand-in-hand, but not always. Sometimes, even when parents strive to be impartial, they still find that each child is more [...] [tvtropes.org]