Your reproductive power may be written in your hands.
But what matters is the symmetry of your two hands and the length of your fingers, not the wrinkles of your palms.
Experiments in mice showed that mutations in the single gene Hox not only affected the development of numbers, but also the development of ovaries and tests.
So John Manning of Liverpool University and his colleagues decided to see if there was any connection between hand type and fertility.
They measured the hands of 60 men and 40 women attending infertility clinics.
Some people have serious fertility problems, while others are healthy partners.
Manning found those with the lowest symmetry in their hands.
One hand is not a mirror image of the other
The number of sperm is the least, and the sperm vitality is the lowest.
"The digital asymmetry predicts the number of sperm that ejaculate each time," he said . ".
"The more asymmetric, the less sperm there is.
"His 12 subjects had little sperm production and the ofup between their hands was asymmetrical to 4mm.
Manning also observed the relative length of the finger.
For reasons that no one can explain, the male ring finger is often longer than the index finger, while the female ring finger is often the same length.
Manning found that men whose ring finger is much longer than their index finger often have higher levels of male sex hormone testosterone, which plays a role in fertility.
In contrast, in women, longer index fingers are associated with higher levels of estrogen and estrogen, both of which are key hormones for female reproduction.
Manning believes the relative length of the two fingers will be a strong predictor of fertility, but warns that more research is needed.
Since trait appears to be fixed in the womb, it may reveal other developmental disorders such as autism.
"You are opening a window for the person's condition in the womb," he said . ".