The first key
Some sources claim that eating foods or vitamin supplements, such as folic acid can help increase the chances of having twins, but you should ask your doctor first.
The second key
Some studies have found that postmenopausal women have many chances to get pregnant, but we do not advise you to wait like this .
The third key
Some foods, such as beans and sweet potatoes can also help you quickly have twins.
The fourth key
If you have children and you should breastfeed to increase the chances of having twins.
Five tips
External fertilization is the best way that can help you to have twins.