Why Some Women Are More Likely To Have Twins Than Others

Why Some Women Are More Likely To Have Twins Than Others

Twins tend to run in families, and now researchers have identified two genes that make women more likely to conceive nonidentical twins. Both genes are related to the production and processing of the hormone that helps oocytes (egg cells) mature.

“There’s an enormous interest in twins, and in why some women have twins while others don’t,” study co-author Dorret Boomsma, a biological psychologist at Vrije Universiteit Amsterdam, said in a statement. “The question is very simple, and our research shows for the first time that we can identify genetic variants that contribute to this likelihood.”

Odds of twins

There are two ways that a woman may conceive twins. In one case, her ovaries release two eggs at the time of ovulation, and both are fertilized and become embryos; this results in fraternal, or nonidentical, twins. In contrast, identical twins are conceived when one embryo splits into two early in its development. Read the full story ….