The discovery of two genes that increase a woman's chances of having non-identical twins could help develop better IVF treatments, researchers say.
Queensland University of Technology scientists have found women with two genetic variants are 29 per cent more likely to have dizygotic or non-identical twins.
The first variant is close to the gene that causes women to generate more eggs per cycle.
The second is linked to the gene found to make women more sensitive to hormones released along with an egg.
QUT associate professor Daly Nyholt said the research had significant implications for fertility treatment.
Prof Nyholt said women with the first variation tended to have more children at a younger age because they were more fertile.
"But you end up depleting you storage of eggs sooner and mostly you end up having menopause earlier," he said.
But Prof Nyholt said it was the discovery of the second variant that was particularly exciting given the women who had it were particularly sensitive to the hormones released along with the eggs.
He said the discovery could help reduce the health risks associated with women receiving dosages of hormones that were too high during IVF treatment.
Prof Nyholt hopes the results will lead to the development of a gene test that could be used to create customised fertility treatments based on a woman's genetic make-up.
Although less reliable, a genetic test could also be used to identify when it was the best time for a woman to have children, based on whether she had the first variant.
The Brisbane researchers - in conjunction with those in Iceland, the Netherlands and America - had their findings published in the American Journal of Human Genetics on Friday.