I think it's clear that there is a biological reason for the male attraction to breasts.

  1. Men can identify women by the look of their breasts, the curvature, the size and pattern of their nipples, and any scars. Men need only look at a womans breasts once or twice to be capable of identifing that woman.
  2. It's the most well defined physical feature that a woman possesses. Sure, lots of women have blue eyes, or blonde hair, short hair, long hair, a blue sweatshirt, but how many of them have DD breasts? Granted, any physical feature can be a mark-maker in the mind of a man, but breasts can't be faked, you have to physically modify them or do something painful or odd to them, like use a wonder bra.
  3. The vast majority of men have this attraction! You are never going to find a hetrosexual man that dislikes breasts! If you do, he's defective! Every man has a certain way he likes his girlfriends breasts to be, pouting, large, well rounded, each the same size, etc.