Twins: blood, milk and society

Well...the title is a little creepy, but sums up the melange in this report, Study finds that a woman's chances of having twins can be modified by diet. But there is more than diet, researchers have long known that genetics plays a role in twinning rates, it is heritable in that some proportion of the population variation correlates with genotypic variation. And we also know that the rise of fertility medicine has resulted in a boom of multiple births in the modern world. Twinning then neatly encapsulates the manifold aspects of many phenomena of interest which exhibit a biological angle. The researcher found that vegan women had 1/5 the twinning rates as non-vegan women. I don't have access to the original paper in The Journal of Reproductive Medicine, so I don't know how well variables were accounted for, but the magnitude of the difference seems great enough that given a ...