A pair of Vietnamese fraternal twins have been confirmed to have different fathers, a local genetic association has told the BBC. The twins had their DNA tested after their family noticed they looked different, said local reports.
当地一家遗传机构接受BBC采访时透露，一对越南的异卵双胞胎已被证实来自不同的父亲。据当地媒体报道，该双胞胎在其家属觉察长相不同后，接受了DNA测试。
The occurrence, known as heteropaternal superfecundation, is rare with few publicly known about. It happens when a woman's eggs are fertilised by two men within a short period of time.
发生的这一案例被称为异父超级受精，这是一种鲜为公众所知的罕见案例。这只会发生在女性的一个卵子在短时间内被两名男性的精子受精的情况下。
Professor Le Dinh Luong, president of the Hanoi-based Vietnam Genetic Association which did the DNA testing, said the results were "100% correct" in what he called "an extremely rare case".
总部位于河内的越南遗传学会负责了本次DNA测试，其董事长Le Dinh Luong教授表示，这个“极为罕见的案例”的测试结果“百分百正确”。

"There are only less than 10 known cases of twins with different fathers in the world. There might be other cases but the parents and/or the twins were not aware of it or didn't want to announce it," he told the BBC's Nga Pham.
他告诉BBC的记者Nga Pham称：“世界上仅有不到10例这种拥有不同父亲的双胞胎案例。当然也可能存在有其他案例，但其父母或双胞胎并没有意识到或者不想公布。”
He declined to give further details citing client confidentiality, but added that local reports stating the twins' location, names and timeframe were inaccurate.
他拒绝进一步提供关于该用户隐私的细节，但他补充说道，当地报道公布双胞胎的地址、姓名和出生时间表是不正确的。
Reported cases are very rare - the last case was in 2015 involving twin girls in New Jersey, only the third such case to ever occur in the US. Turkish media reported a similar case in 2010 involving twin boys.
被报道的类似案例极少。上一个类似案例是2015年新泽西州的两个双胞胎女孩，这也仅仅是在美国发生的第三个案例。此外，土耳其媒体也于2010年报道过一对双胞胎男孩的类似案例。