1. Scientists
believe that the number of twin conceptions greatly outnumbers the number of
twin births. Twin conceptions
are much more common than many people realize. Of course, these conceptions do
not always result in the birth of two healthy babies. Very often, one of the
fertilized eggs or embryos will be reabsorbed into the mother's womb in a
phenomenon called "vanishing twin syndrome."
2. The incidence of twin types and genders are oddly symmetrical. These facts about twinning are sure to leave you in awe. One third of all twins born are identical, one third are same sex fraternal, and one third are male/female fraternal. Of the identical twins, half are male.male and half are female/female. Of the same sex fraternal, half are male/male, and half are female/female.
3. Twins do not
have to be born on the same date. In
fact, they can be born surprisingly far apart. The longest recorded gap between
twin births is 85 days. How does this happen? The simplest explanation comes
when one twin is born just before midnight and the other after. In cases where
there is a longer gap, it's often because one twin is born early due to
complications, while the other is left in the womb to further develop. This is
much safer for the second baby and can help improve survival rates.
4. Identical twins
have different fingerprints. Some people might
think that identical twins are the same right down to those whorls and swirls
on their fingerprints, but while identical twins share most of their genetic
material, identical fingerprints aren't among them. While the fingerprints may
be very similar, on close examination it is possible to tell them apart – much
like the twins themselves.
5. About 25% of identical twins are
called mirror image twins. This
means that they are, in fact, identical, but only in the way that your
reflection in a mirror is an identical image of you. For example, if one twin
has a mole under her right eye, the other will have it under her left eye.
Scientists think this is due to the fertilized egg splitting later than the
norm for identical twins, around nine to twelve days after fertilization.
6. Twins often
develop their own language. This phenomena is
called idioglossia. It's something that has fascinated people about twins for
years, but it's really a relatively simple and easily understandable process.
It happens when one twin models the disordered or incorrect speech of the
other, leading to both twins using the same grammatical or speech sound errors.
It sounds like a foreign language, but is really just a normal part of
cognitive development. 40% of
twins invent their own language.
7. Twins share DNA,
but it is not identical. While
identical twins come from the same sperm and egg, their DNA isn't necessarily
identical, according to new research. Scientists used to think differences in
twins were due to environmental factors; they now know that isn't the only
force causing variations. Genetic studies have demonstrated that there are
certain points where twins will veer away from one another, with one carrying
different or multiple copies of the same gene.
8. Certain diets
may increase your chances of having twins. What a woman eats
can help increase her chances of having twins, or so researchers think. While
genetics obviously plays a big role, diet can also influence this phenomenon.
Researchers have found that women who eat dairy and animal products are much
more likely to have twins than those that don't. This is likely due to a
protein called IGF that increases the sensitivity of the ovaries to hormones
that cause ovulation.
9. Fraternal twinning is genetically
predisposed. Identical twinning is random. Fraternal twinning
is the result of a woman releasing multiple eggs at the same time, and is
largely the result of a genetic predisposition to release this extras.
Identical twins, however, are the result of a random split of a single egg,
something which cannot be genetically predisposed. In recent years, the number
of fraternal twins has risen in response to fertility treatments, while the
number of identical twin births has stayed the same.
10. 27 lbs and 12oz
is the heaviest combined birth weight of any set of twins. if you think it
would be rough to carry around and deliver one 14-pound baby, then imagine
doing it with two. That's just what happened in this case, the largest twin
birth on record. Of course, it doesn't hold a candle to the largest singleton
birth weight of 23 pounds.
11. Turns out there are ways to up the chances you'll deliver two
bouncing babies. Being tall is one of them. Past research has found that taller
women have more of an insulin-like growth factor that has been linked to both
height and the rate of twins.Those who birthed two or more
children were on average more than an inch taller than other mothers, according
to the study published in September 2006 in the Journal of Reproductive
Medicine. As a woman ages, she's also more likely than her younger counterparts
to have multiple births.
12. Birth rate statistics for identical twinning
have remained stable over the years, despite the overall increase in twins and
multiples since the late 1980's. The odds of having identical twins is about 3
in 1,000, whereas the birthrate
for all twins is about 32.2 in 1,000.
13. Over 50% of twins are born before 37 weeks.
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