A recent study has found that insulin-like growth factor present in dairy products may increase the chance of dizygotic twinning. Specifically, the study found that vegan mothers (who exclude dairy from their diets) are one-fifth as likely to have twins as vegetarian or omnivore mothers, and concluded that "Genotypes favoring elevated IGF and diets including dairy products, especially in areas where growth hormone is given to cattle, appear to enhance the chances of multiple pregnancies due to ovarian stimulation."
From 1980–97, the number of twin births in the United States rose 52%. This rise can at least partly be attributed to the increasing popularity of fertility drugs like Clomid and procedures such as in vitro fertilization, which result in multiple births more frequently than unassisted fertilizations do. It may also be linked to the increase of growth hormones in food.
Read more about this topic: Twin
Other articles related to "demographics":
... There were 252 households out of which 31.7% had children under the age of 18 living with them, 70.2% were married couples living together, 3.2% had a female householder with no husband present, and 22.6% were non-families. 17.1% of all households were made up of individuals and 6.3% had someone living alone who was 65 years of age or older ...
... There were 31 households out of which 32.3% had children under the age of 18 living with them, 45.2% were married couples living together, 16.1% had a female householder with no husband present, and 22.6% were non-families. 19.4% of all households were made up of individuals and 3.2% had someone living alone who was 65 years of age or older ...