When this New York Times article came out last month, I rejoiced with our small-busted sisters.  The only thing wrong with the article was this quote:

In recent years, as people’s weight has ballooned, breasts (mostly made up of fat) have only gotten larger, and commensurately bra cup sizes, too. K-cups now exist.

I’m sure you’ve read this assumption elsewhere as well–that the higher average bra cup size is due to rising obesity rates.  Finally, this Australian news article gives support for what you and I have always known.

Australian research has confirmed what women already know: big breasts sometimes sit on petite bodies and tiny bosoms can rest on large frames. In other words, most of the genes determining breast size are separate from those that dictate how large women are. By studying female twins, researchers investigated how breast size was inherited and the degree to which this heritability was shared with body mass index. The study in Twin Research and Human Genetics found genes were responsible for 60 per cent of bra cup size. Of this genetic variance, just one-third was in common with genes influencing BMI; two-thirds was unique to breast size.

(Nothing after the jump.)