This twins trivia quiz has 60 free questions with answers and covers everything twin-related except the baseball team: the biology of identical and fraternal twins, mirror twins and conjoined twins, the countries and towns where twins are most common, and the science of vanishing twins, superfetation, and twins with different fathers. It also runs through the famous pairs, from Romulus and Remus and Castor and Pollux to the Olsens, the Sprouses, the Winklevosses, the Bryan brothers, and the astronaut Kelly twins. It was built to double as a free twin trivia baby shower game: every question is clean, fun, and multiple choice, so guests who don't know a zygote from a zodiac sign can still guess along. Difficulty runs from easy warm-ups to a few real stumpers for the twin parents in the room. Every answer has been checked against a reference page (mostly Wikipedia and a peer-reviewed twinning-rate study), so you can trust the answers when the arguments start.
30 of 60 questions with answers and explanations. Play the quiz
Q 01Twins that develop from a single fertilized egg that splits into two embryos are called what?
Monozygotic
Monozygotic twins are the 'identical' kind; dizygotic twins each grow from a separate egg. The Greek roots literally mean 'one yolk' versus 'two yolks.'
Q 02Roughly what share of human births are twins?
About 1 in 90
That works out to about 1.1 percent of births. Identical twins are much rarer, at roughly 3 to 4 per 1,000 births.
Q 03The Yoruba people of West Africa have the world's highest twinning rate. Roughly how many twin sets are born per 1,000 live births there?
About 45
That is 90 to 100 twins per 1,000 births, several times the global average. Twins hold a special place in Yoruba religion, where they are called Ibeji.
Q 04A 2011 global study found the highest national twinning rate, 27.9 per 1,000 births, in which country?
Benin
The same study found the lowest rates in South and Southeast Asia and Latin America, where twinning runs below 9 per 1,000.
Q 05Igbo-Ora, nicknamed the 'Twin Capital of the World,' is a town in which country?
Nigeria
Locals often credit the diet, and researchers have looked at a chemical found in yam peelings, though nothing has been proven.
Q 06In Yoruba tradition, the first-born twin is named Taiwo. What is the second-born twin called?
Kehinde
Yoruba belief flips the usual order: the second-born is considered the elder, having sent the first out to check whether the world was fit to enter.
Q 07Which Rio Grande do Sul town is nicknamed 'Land of Twins' for its twinning rate?
Candido Godoi
A theory blaming Nazi doctor Josef Mengele made headlines, but geneticists point to a founder effect among the town's German and Polish settlers, and the twin births predate his arrival.
Q 08'Mirror image' twins, with reversed features, result when the egg splits at what point?
Around days 9 to 12
The later-than-usual split can leave one twin right-handed and the other left-handed, with hair whorls and even birthmarks on opposite sides.
Q 09Do identical twins have identical fingerprints?
No, never
Fingerprints are shaped partly by contact with the womb, so each twin touches a different environment and grows unique ridges. Their DNA is nearly identical, though.
Q 10Fraternal twins run in families because some women inherit a tendency to do what?
Release more than one egg per cycle
This tendency to hyper-ovulate is genetically linked, which is why fraternal twins cluster in families. Identical twinning, by contrast, has no known genetic link.
Q 11Compared with younger mothers, the rate of fraternal twins roughly doubles for mothers over what age?
35
Rising maternal age and fertility treatments together drove a 52 percent jump in U.S. twin births between 1980 and 1997.
Q 12By 2011, roughly what share of US twin births were estimated to result from IVF and similar technology?
36%
Fertility drugs and IVF often produce more than one embryo, which is a big reason twin births climbed so steeply from the 1980s onward.
Q 13Researchers suspect as many as how many pregnancies begin as multiples but end with a single baby?
1 in 8
In most cases the lost twin is reabsorbed so early that the mother never knew there were two, which is why early ultrasounds keep turning them up.
Q 21Chang and Eng Bunker married Adelaide and Sarah, two sisters with which surname?
Yates
The double wedding took place in 1843, and the twins eventually kept two separate households, alternating three days at each.
Q 22According to legend, the twin founders of Rome were suckled as infants by which animal?
A she-wolf
The cave where it supposedly happened is called the Lupercal. Roman tradition put the city's founding at around 753 BC.
Q 23Which pair of mythological twins was placed in the sky as the constellation Gemini?
Castor and Pollux
In the myth only Pollux, son of Zeus, was immortal; when mortal Castor died, Pollux asked to share his immortality and the two became stars.
Q 14Fraternal twins with two different biological fathers are the result of a phenomenon with what name?
Heteropaternal superfecundation
It happens when two eggs released in the same cycle are fertilized by different men. Among disputed-paternity twin cases in one study, it turned up about 2.4 percent of the time.
Q 15How rare is superfetation, conceiving again while already pregnant, in humans?
Fewer than ten confirmed cases worldwide
The result is 'twins' of different gestational ages in the same womb. It's much more common in animals such as hares and badgers.
Q 16Possibly the longest gap between twin births, 97 days, was recorded in which German city?
Cologne
Delayed-interval delivery can let doctors keep the second twin in the womb after the first arrives prematurely, so some twins end up with different birthdays, months, or even years.
Q 17A private language developed by twins that only the two of them understand is called what?
Cryptophasia
The name comes from Greek for 'secret speech.' It usually fades as the children learn the language everyone else speaks.
Q 18Roughly how often do conjoined twins occur?
About 1 in 50,000 pregnancies
Most conjoined twins are girls, by a ratio of about three to one, and the most common type is joined at the chest.
Q 19As of 2019, how many cases of semi-identical 'sesquizygotic' twins had been documented?
Two
The second case, in Brisbane in 2019, showed the twins shared 100 percent of maternal and about 78 percent of paternal DNA, the result of one egg being fertilized by two sperm.
Q 20Chang and Eng Bunker, the original 'Siamese twins', were born in Siam, now called what?
Thailand
The brothers settled in North Carolina, married two sisters, and fathered 21 children between them, none of them conjoined.
Q 24The Gemini twins of Greek myth had a famous sister. Who was she?
Helen of Troy
All three were children of Leda; the twins were known collectively as the Dioscuri, 'sons of Zeus,' and served as patrons of sailors.
Q 25Gemini, the zodiac sign of the twins, is ruled by which planet?
Mercury
Gemini is the third sign of the zodiac and an air sign; NASA borrowed the name for its two-astronaut spacecraft program in the 1960s.
Q 26In the Book of Genesis, the twin Esau sold his birthright to his brother Jacob in exchange for what?
A bowl of stew
Esau was the firstborn; Jacob later disguised himself in Esau's clothes to claim their blind father Isaac's blessing as well.
Q 27What name was given to Elvis Presley's stillborn twin brother, delivered 35 minutes before him?
Jesse Garon
The name rhymed with Elvis's own middle name, Aron. Elvis was raised as an only child in Tupelo, Mississippi.
Q 28Which actor played both Kray twins in the 2015 film Legend?
Tom Hardy
The Krays ran the East End 'Firm,' owned the nightclub Esmeralda's Barn, and were photographed by David Bailey before being jailed for life in 1969.
Q 29Mary-Kate and Ashley Olsen got their start sharing the role of Michelle Tanner on which sitcom?
Full House
Despite looking alike, the Olsens are fraternal twins. They went on to found the luxury fashion label The Row in 2006.
Q 30What was the 1990s sitcom starring Tia and Tamera Mowry as twins separated at birth?
Sister, Sister
ABC cancelled it after two seasons and The WB picked it up for four more. Both sisters were born in Gelnhausen, West Germany.