Newly Wed Couple Brad Pitt and Angelina Jolie
Angelina Jolie, a celebrity mother who endorses breastfeeding. Reuters

With the world fascinated with twins, two popular celebrities, Angelina Jolie and Jennifer Lopez have twins with their respective husbands.

Angelina Jolie had Knox Leon and Vivienne Marcheline on July 12, 2008 with actor Brad Pitt. They were delivered through C-section in France and are the fifth and sixth children for the couple.

Superstar singer, Jennifer Lopez, had Max and Emme in 2008 with her then husband, Marc Anthony. The twins appeared in People magazine just a month after their birth.

People love hearing about those who have twins or multiple children at a go as some people feel that having one pregnancy with multiples will help them "get it over with." Some other people are just excited about it and then there are those who have fertility problems who want to avoid painful treatments. Below are a couple of theories that researchers suggest might help while trying to conceive twins.

It is said that eating yams help in having twins as it has a certain chemical that helps the woman have twins. Also, studies have showed that during pregnancy, the woman who breastfeeds has a higher chance of conceiving twins as there is a loss of calcium while nursing.

Age might be just a number but for those who wish to conceive twins, being older is advantage as there might be an increase in ovulation which leads to more chances of having twins.

Another advantage can be if they were a twin themselves as this can result in a higher rate of having multiple kids at a go. A maternal or family history of having twins increases the chance of having twins, either dizygotic or fraternal twins as this provides the woman the ability to ovulate two or more eggs during ovulation.

Fertility drugs like Clomid also seem to increase chances of conceiving twins as multiple eggs could possibly be released during the time of ovulation. Unfortunately, there are certain risks associated with drugs and are suggested to only those who have trouble with conceiving. Also, those women undergoing in vitro fertilisation and other fertility treatments have a higher risk of having twins, that are dizygotic, monozygotic or identical, or other multiples.