ABOUT TWINS – TWINNINGS – TWINKINIS
Twins in animal biology is a form of multiple birth in which the mother gives birth to two offspring from the same pregnancy, some of the same sex, others of the opposite.
Triplets refers to three offspring from the same pregnancy. The general term for more than one offspring from the same pregnancy is multiples. A fetus alone in the womb is called a singleton.
Human twins are two individuals who have shared the uterus during a single pregnancy and are usually, but not necessarily, born in close succession. Due to the limited size of the mother’s womb, multiple pregnancies are much less likely to carry to full term than singleton births, with twin pregnancies lasting only 37 weeks on average, 3 weeks less than full term. Since premature births can have health consequences for the babies, twin births are often handled with special precautions.
Types of twins
There are five variations of twinning that commonly occur. The three most common variations are all fraternal: (1) male-female twins are the most common result, at about 40% of all twins born; (2) female fraternal twins (sometimes called sororal twins); (3) male fraternal twins. The last two are identical: (4) female identical twins and (5) (least common) male identical twins. Male singletons are slightly, about 5%, more common than female singletons. However, males are also more susceptible than females to death in utero, and since the death rate in utero is higher for twins, it leads to female twins being more common than male twins.
Fraternal twins (commonly known as “non-identical twins”) usually occur when two fertilised eggs are implanted in the uterine wall at the same time. The two eggs form two zygotes, and these twins are therefore also known as dizygotic as well as “biovular” twins. When two eggs are independently fertilised by two different sperm cells, fraternal twins result.
Studies show that there is a genetic basis for fraternal twinning. However, it is only the female partner that has any influence on the chances of having fraternal twins as the male cannot make her release more than one ovum. Fraternal twinning ranges from 6 per thousand births in Japan (similar to the rate of identical twins) to 14 and more per thousand in some African states.
Identical twins occur when a single egg is fertilized to form one zygote (monozygotic) which then divides into two separate embryos. Although their traits and physical appearances are not exactly the same due to environmental conditions in both the womb and outside the womb, they do have the same DNA. This is not considered to be a hereditary trait, but rather an anomaly that occurs in birthing at a rate of about 3 in every 1000 deliveries worldwide, regardless of ethnic background. The two embryos develop into fetuses sharing the same womb. When one egg is fertilized by one sperm cell, and then divides and separates, two identical cells will result. Most of the time in identical twins the zygote will split after 2 days, resulting in a shared placenta, but two separate sacs. These are called monochorionic, diamniotic (“mono/di”) twins. In about 1% of identical twins the splitting occurs late enough to result in both a shared placenta and a shared sac called; monochorionic, monoamniotic (“mono/mono”) twins. Finally, the zygote may split extremely late, resulting in conjoined twins. Di/di twins have the lowest mortality risk at about 9%, although that is still significantly higher than that of singletons.
Monozygotic twins generally look alike. Fine physical details such as fingerprints will differ. As they mature, identical twins often become less alike because of lifestyle choices or external influences. Genetically speaking, the children of identical twins are half-siblings rather than cousins. It is estimated that there are around 10 million identical twins and triplets in the world.
The likelihood of a single fertilization resulting in identical twins appears to be a random event, not a hereditary trait, and is uniformly distributed in all populations around the world. This is in marked contrast to fraternal twinning which ranges from about 6 per thousand births in Japan (almost similar to the rate of identical twins, which is around 4-5) to 15 and more per thousand in some parts of India (and up to 24 in the US, which might mainly be due to IVF, in vitro fertilization). The exact cause for the splitting of a zygote or embryo is unknown.
Studies have shown that identical twins reared in different environments share similar personality traits, mannerisms, job choices, attitudes, and interests. These findings add to the belief that many behaviors are derived from genes.
Identical twins have identical DNA but differing environmental influences throughout their lives affect which genes are switched on or off. This is called epigenetic modification. A study of 80 pairs of human twins ranging in age from 3 to 74 showed that the youngest twins have relatively few epigenetic differences. The number of epigenetic differences between identical twins increases with age. 50-year-old twins had over three times the epigenetic difference of 3-year-old twins. Twins who had spent their lives apart (such as those adopted by two different sets of parents at birth) had the greatest difference. However, certain characteristics become more alike as twins age, such as IQ and personality. This phenomenon illustrates that genetics play a dominant role in many aspects of human characteristics and behavior.
Born to Vasanthi and Venkatesh Kini in 1964 in the most beautiful of coastal towns of Mangalore on 6th February 1964, Ravindra and Narendra were identical twins and brothers of Vidya who was about 16 months older to them. Early years were aptly captured by the enthusiasm for photography by their uncle Mohandas Baliga with some very interesting black and white pictures.
No ordinary lady could have possibly raised these two active and hyper boys. Always seeking mischief, action, attention and trouble, there could be books written about their childhood episodes – the narrator can only be their dear mother – who was the only one who could tell them apart until they started to dress in different clothes in middle school.
Being competitive and athletic, they did not need the rest of the world to tell them that they lived in a world where the fittest survived. So, from waking up to finishing breakfast to getting to the gates, studies, sports and contests, both competed hard with each other.
This self appraising system worked well all thru their school and college days. At the 11th grade, they decided to take different tracks. Ravindra took Commerce- proceeding to become a Cost Accountant and Narendra took Science- proceeding to become an Industrial Engineer.
Stories and episodes that highlight facts and musings about twins are many. I guess a separate blog of those is justified.
At the time of going to press, Ravindra lives with his wife Chandrika and two kids Abhay and Arjun in Bangalore. Narendra lives with his wife Sandhya and kids Pooja and varoon in San Ramon, CA. Despite miles and oceans apart, there are a few interesting parallels that have continued to leave the rest of the world wondering if there is a grand old conspiracy that these two have that they happen to have co-incidences happening on all walks of life. As for their opinion in the matter – they always have their standard reply – SMILE!
- Alexander Helios and Cleopatra Selene (1st century BC), twin children of Mark Antony and Cleopatra.
- Fausta and Faustus Cornelius Sulla (1st century BC), twin children of Lucius Cornelius Sulla.
- Saint Benedict and Saint Scholastica (6th century), founders of the religious Benedictine Order for monks and nuns.
- Berenguer Ramon II, Count of Barcelona and Ramon Berenguer II, Count of Barcelona, born in 1054.
- Waleran de Beaumont, Count of Meulan and Robert de Beaumont, 2nd Earl of Leicester, born in 1104.
- King Henry II of Castile and twin brother Fadrique of Trastamara (killed 1358).
- King James II of Scotland and Alexander Stewart, Duke of Rothesay, born in 1430.
- Jeanne and Victoire de Valois (born and died 1556), twin daughters of Henry II of France and Catherine de’ Medici.
- Henry Vaughan, poet, and Thomas Vaughan, philosopher, born in 1622.
- Hamnet and Judith Shakespeare, twin son and daughter of William Shakespeare.
Twins in sports
- Antonio Rodrigo Nogueira and Antonio Rogerio Nogueira, mixed martial artists
- Kenya Dandridge and Kidra Dandridge , basketball players
- Alberto and Carlos Arroyo, basketball players; Alberto in the BSN, Carlos in the National Basketball Association (NBA)
- Archil and Shota Arveladze (born 1973), Georgian international footballers
- Herbert and Wilfred Baddeley, British tennis players
- Ronde and Tiki Barber (born 1975), National Football League (NFL) players
- Antonia and Ferdinand Becherer, German Olympic figure skate team
- Alec and Eric Bedser (born 1918), England cricketers
- Frank and Ronald de Boer (born 1970), Dutch international footballers
- Bob and Mike Bryan, pro tennis players, doubles champions
- Josh and Daniel Bullocks (born 1983) National Football League (NFL) players
- Heather and Heidi Burge, former WNBA players
- José and Ozzie Canseco (born 1964), Major League Baseball players
- Dionísio and Domingos Castro (born 1963), Portuguese long-distance runners
- David and Donald Cockatoo-Collins, AFL footballers
- Jarron and Jason Collins, NBA basketball players
- Alissa and Amber Czisny, American figure skaters
- Philipp and David Degen, Swiss national footballers
- Jorge and Julio Dely Valdes, Panamanian international footballers
- Jeroen and Henrico Drost, Dutch football (soccer) players
- Mark and Michael Evans (born 1957), Canadian rowers
- Caroline and Georgina Evers-Swindell, New Zealand world champions double sculls (rowing).
- Stephen and Matthew Febey, AFL footballers
- Peter and Chris Ferraro, National Hockey League players
- Miguel and Javier Flaño, Spanish football (soccer) players
- Joey and Stephen Graham, NBA basketball players
- Horace and Harvey Grant (born 1965), NBA players
- Michael and Marcus Griffin (born 1985), National Football League (NFL) 2007 draft DB prospects (Texas) likely to go early
- Tim and Tom Gullikson, pro tennis players, doubles champions
- Paul and Morgan Hamm (born 1982), Olympic gymnasts
- Don and Ron Harris (born 1961), professional wrestlers
- Alvin and Calvin Harrison, American sprinters and Olympic athletes
- Earl and Dave Hebner, TNA Wrestling referees
- David and Kenny Irons (born 1983), National Football League (NFL) 2007 draft prospects at DB & RB (Auburn)
- Jenny and Susanna Kallur, Swedish hurdle runners
- René and Willy van de Kerkhof (born 1951), Dutch international footballers
- Tai and Tasesa Lavea (born 1980), New Zealand former NRL footballers (Tasesa now plays rugby union in New Zealand)
- Nathan and Ryan Lonie, AFL footballers
- Alistair and Stewart Lord, AFL footballers
- Henrik and Joel Lundqvist, Swedish ice hockey players
- Phil and Steve Mahre, American skiers
- Hamish and James Marshall, New Zealand cricketers
- Coco and Kelly Miller (born 1978), WNBA players
- Mildred and Marianne Muis (born 1968), Dutch swimmers
- Akona and Odwa Ndungane (born 1981), South African rugby union footballers
- Philip Neville, English footballer, and Tracey Neville, English netballer
- Dennis and Gérard de Nooijer, Dutch footballers
- Amanda and Isabelle Nylander, Swedish figure skaters
- Emilia and Erika Nyström, Finnish beach volleyball players
- Javier and Ricardo Otxoa Palacios (born 1974, Ricardo died in 2001), Spanish cyclists
- Andreas and Thomas Ravelli, Swedish football players
- Ann and Claire Recht Division I women’s volleyball
- Chris and Brad Scott, AFL footballers
- Daniel and Henrik Sedin, Swedish ice hockey players
- Patrik and Peter Sundstrom, Swedish ice hockey players
- Ron Sutter and Rich Sutter,(born 1963) Canadian,NHL hockey players
- Mike and Todd Shane, professional wrestlers
- Dick and Tom Van Arsdale, former NBA basketball players
- Roel and Mansueto Velasco (born 1972), Filippino boxers
- Darryl and Shane Wakelin, AFL footballers
- Mark and Steve Waugh (born 1965), Australian cricketers
- Dora and Cora Webber (born 1958), American women world champion boxers
- Marcin and Michał Żewłakow (born 1976), Polish international footballers
- Bengt and Björn Zikarsky (born 1967), German freestyle swimmers
- Guillermo Barros Schelotto and Gustavo Barros Schelotto (born 1973), Argetine Football (soccer) players
- Hamit and Halil Altıntop; Turkish soccer players.
- Michael Reider and Jeffrey Reider (born 1982), Hungary Football (soccer) players
- Jon and Robert Dohring, (born 1986), NCAA Division III 1-meter and 3-meter springboard national champions.
Twins in politics
- Angela Eagle and Maria Eagle, British members of Parliament.
- Jarosław and Lech Kaczyński, Polish prime minister and president respectively; formerly child actors.
Twins in Business
- David and Frederick Barclay (1934 – ) are British businessmen. Their Press Holdings company owns The Business, The Spectator magazine, The Telegraph Group Limited.
Twins in science
- Michael and Alex Bronstein, co-inventors of a three-dimensional face recognition technology
- Mark E. and Scott J. Kelly, first astronaut twins
- Kian and Remee Hodgson, twins genetically born from biracial parents; One twin is black, the other white
- Alicia and Jasmine Singerl, similar set of twins as Kian and Remee Hodgson
- Jessica and Flora Walker – co-inventors of two-dimensional face recognition technology