Jacob was quiet and studious, finding his pleasures in and around the home; Esau was macho and active, enjoying being out and about.
The family dynamics were full of tension, son against son, and at least on some days, parent against parent.
Sforno says Isaac loved Esau for selfish reasons, namely that Esau brought him the sort of food he liked, and Rebekah loved Jacob because he was so different from Esau.
Others say that the cleavage was ideological and each parent liked the philosophy of life that their particular favourite son represented.
The situation recurs over and over again throughout history, not excepting our own generation.
A week or so ago in Parashat Vayyera, we found this discussion happening between Abraham and God.
God tells the patriarch to take the son he loves and offer him on the mountain.
“The one I love?” says Abraham; “I love them both!”
Yet we all know families where a parent plays favourites, to the extent that they shower the preferred child with both material and emotional largesse.
What a recipe for disaster in years to come!