Twins from different fathers in one womb

Siblings can have different fathers; can twins
born of a woman have two fathers? The
straight answer is yes. Twins could be
“bipaternal.” This phenomenon occurs quite
rarely (1 in a billion to be exact), but several
pairs of non-identical twins have been born,
tested and found to be the products of one
womb, one pregnancy, but two fathers.
It is often assumed that for twins, both eggs
were fertilized during a single act of
intercourse. However it is quite possible for one
egg to be fertilized during one act of
intercourse, and the other during another if the
woman has intercourse with two men within
hoursNormally, women ovulate only one healthy egg
per cycle. Fraternal twins are born when
women ovulate two healthy eggs and both get
fertilised. But it is also possible for two eggs
to be ovulated during the same cycle and
fertilised at different points within the five-day
fertility window resulting in twins. This process
is known as “superfecundation”. What this
means is that each egg can be fertilised by
different sperms.
If a woman ovulates two or more eggs and she
has sex with more than one man while she’s
fertile, “heteropaternal superfecundation” can
occur, if the eggs get fertilised by sperm from
the two different fathers within the same
ovulation period.
Medical research shows that when a woman
has sex with two men within the same
ovulation window, it can result in bi-paternal
twins, that come when a woman releases two
eggs during ovulation instead of one — and
both eggs are then fertilized.
With bi-paternal twins, each egg is fertilized
by a different man’s sperm. A woman’s eggs
can live up to 24 hours in her reproductive
system. Sperm, on the other hand, can live up
to five days in the woman’s body.
So it is possible that a fertile woman could
have sex with one man and have sex with a
different man another time within the 24 hour
period — and then when her eggs are released,
the two men’s sperm living inside her could
each fertilize an egg.
Marcus and Lucas are twins with two different
fathers. They are one of only three known sets
of twins in the world who are genetic half-
brothers. Their mother Charlotte became ­
pregnant when she slept with ex-husband
Michael and new boyfriend Tommy within 48
hours. Nine months later she gave birth to
twins Marcus and Lucas, who are genetic half-
brothers because they were fathered by both
Marcus was fathered by Michael and Lucas by
Tommy. Charlotte, who already had two sons
by Michael Nielsen, divorced him in August
2004. She began dating Tommy even as
Michael still hoped to get back together with
her and in the heat of the moment they ended
up in bed together. Charlotte kept quiet about
the incident with Michael which was a one-off
and went to bed with Tommy. She later
discovered she was pregnant with twins and
decided to inform both men either could be
father of the twins.
Marcus and Lucas were just a couple of weeks
old when it was discovered they didn’t look
alike. Tommy and Michael took a DNA test to
find out for certain that the boys had different
fathers. The test proved the twins did indeed
have different fathers. It stated: “The results do
not imply that the children Lucas Hilbrandt
Nielsen and Marcus Hilbrandt Nielsen have the
same biological father. The probability of this
preclusion exceeds 99.99 per cent.”
Similar cases of bi-paternal twins have popped
up over time. In May 2015, a case in New
Jersey made news when a court ruled that a
father did not have to pay child support for a
second twin because DNA evidence showed
that he was a father to only one.
The mother gave birth to twin girls and named
a romantic partner, as the father of both
children when applying for public assistance.
But after she admitted that she had sex with
another unidentified man within a week of
having had sex with the bonafide partner, a
DNA test was ordered. The test results
confirmed both men fathered each of the girls.
CNN also reported fraternal twins in Vietnam
found to have different fathers in an “extremely
rare” case that came to light through a DNA
They had their DNA tested at the Centre for
Genetic Analysis and Technology in Hanoi
because family members had been vocal about
notable differences in the children’s
There are rare cases in which a woman may
ovulate more than once during her cycle,
meaning that two eggs would be released at
different times. There are less than 10 known
cases of twins with different fathers in the
world. Fraternal twins make up about 2
percent of pregnancies and bi-paternal twins
are a fraction of them.
But twins, who don’t look alike, do not
necessarily have separate fathers. Twins who
have the same father can look completely
different and may even appear to be of
different races. Less than one (0.001) per cent
of fraternal twins are from different fathers.
According to Dr. Virginia Beckett of the Royal
College of Obstetricians and Gynaecologists, if
a woman is going to sleep with more than one
partner at the same time it is perfectly feasible
that if she has twins they could have different
“In this case these twins were conceived at the
same time even though the mother did not
have sex with the fathers at the same time.
The sperm from the first man would have been
in her fallopian tube, where it is effective for
three to four days. Then she had sex with the
second man and released two eggs. The eggs,
which live for 24 hours, were fertilised by
different sperm from the different men. The
science is easily explained, but it may have
been less easy for the mother to explain..




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