Doctors say that they have found the identification of the second son's son and two spermatozoa.
Four-year-old boys and girls, Brisbane, Australia, are equal to their mother, but only their father's proportion.
Experts say the phenomenon, which is known as semi-identical or sesquicidal twins, is very rare, and these embryos usually do not survive.
In this case, the first revision in The New England Journal of Medicine is during pregnancy.
The doctors said the mother was 28, who was naturally thinking about it for the first time.
Prof Nicholas Fisk directed a group led by Royal Brisbane and the Women's Ward in 2014 to look after her mother and daughter, said the discovery was made through a regular study.
He said: "The mother's ultrasound showed in six weeks a single placenta and amniotic bag positioning, indicating that the twins were the same.
"However, in the 14 weeks, the ultrasounds were twin men and women, the twins were not the same".
Prof. Fisk added: "It's likely that the egg of the mother at the same time separated two of her father's sperm before spreading".
They are genetically alike, twins and even twins.
Both twins are the same as the single egg cells delivered by a single sperm into two parts: so they share the same genus and DNA.
Two twin beans each twin develop a separate egg and fertilize the egg with a sperm.
Prof. Working with Fisk at Queensland Technology University, Michael Gabbett explained that when eggs are spermed by two sperm, there are three chromosome sets from one mother and two parents.
He said: "The three chromosome groups are incompatible with life and the embryos have not survived.
"In Brisbane sesquizygotic twins, the fertilized egg divides three chromosome sets into two parts, creating twins.
"Some cells have chromosomes in the first sperm, the rest of the cells have chromosomes in second sperm, twins with less than 100 percent of the DNA father's."
FIRST RARE CASE
The first bi-sex twins were reported in the United States in 2007.
The doctor's attention was reached in childhood after identifying the genitals with ambiguity.
In addition to investigating the mixed chromosomes, the doctors had the same boys and girls alike, but they shared the father's half DNA.
Prof. Fisk said that studying twins from all over the world on the lungs as trivia.
He said: "At first, we questioned other cases that were not classified badly or were not reported, 968 twin brothers and their parents analyzed genetic data.
This is your sexual drive as your rampant (and the girls may be surprised).
That is, in any case, you should never use a shower puf
It's no longer twitching
If you suffer from a relaxed leg syndrome, it will be easier for you
Do you think that vitamin tablets waste time? This is what you really need to take, says the government
Can your e-cigarette be allergic? Vaping can lead to deadly reaction and chemical asthma & # 39;
"However, we have not found these data in the other two videos, or the twin ones, the twins in the main general analyzes."
Prof. Fisk added: "This twin is a superb case.
"Doctors may remember that twins are identical, their rare genes are not considered genetic routines."
We pay your stories! Do you have a story in the group of The Sun Online news? Contact us at email@example.com or call 0207 782 4368. WhatsApp can also make videos with 07810 791 502. Click here to load yours.