Scott Alexander in Astral Codex Ten:
From the Dynomight blog: You, Your Parents, And The Hotness Of Who You Marry.
They start with a traditional situation: some romance novel heroine wants to marry a tall, dark stranger. But her parents want her to marry a much older nobleman/doctor/engineer who can provide her with a stable income. Or the gender-flipped version: the young man courts a beautiful debutante, while his parents try to force him to marry the plain-faced daughter of their business partner.
Evolutionary psychology has pat explanations for both sides here. People want attractive partners because attraction correlates with health, fertility, and status (eg the debutante’s wide hips and large breasts mean she’ll be able to give birth and nurse effectively; the stranger’s height means he must be strong and healthy). But people also want wealthy partners from good families, because they’ll be able to give more resources to the children.
Dynomight’s question is: why do the suitors and the parents disagree here? Everyone involved (evolutionarily) wants the same thing: lots of healthy, successful descendants.