1、TWINS!,Their Role in The Nature v. Nurture Debate,Monozygotic Twins,The correct term for identical twins is monozygotic twins. This term notes the fact that the twins form from a single (mono) fertilized egg (zygote). The zygote splits into two parts after conception, resulting in the development of

2、 two individual embryos. Because the two embryos are the result of a single egg/sperm combination, they have the same genetic origins. They have the same DNA. The causes of monozygotic twinning are generally unknown and unidentified. No one really knows why an egg splits; technically its a malfuncti

3、on of the normal development process. Theres no hereditary trait that influences a predisposition to having identical twins. Identical twins do not run in families. Although there are families with a high incidence of identical twins, it is due to chance, coincidence or plain good luck.,Did You Know

4、?,The odds of having identical twins is about 3 in 1000, whereas the birthrate for all twins is about 32.2 in 1000 It is possible, in very rare cases 0.01% - that a set of twins with one boy and one girl can be identical Birth rates for identical twins are consistent across populations; it is the sa

5、me regardless of race, geography or maternal age.,The Other Minnesota Twins,You take it for granted that you are a totally unique person, different from everybody else on Earth. And you understand that everybody else is also unique. On a most basic level, identical twins are fascinating because they

6、 challenge this truth. They are unique people, of course, but theyre eerily like each other. Consider the extreme case of the Jim twins. Identical twins Jim Lewis and Jim Springer were only four weeks old when they were separated; each infant was taken in by a different adoptive family. At age five,

7、 Lewis learned that he had a twin, but he said that the notion never truly soaked in until he was 38 years old. Springer learned of his twin sibling at age eight, but both he and his adoptive parents believed the sibling had died. The two were finally reunited at age 39. The similarities the twins s

8、hared not only amazed one another, but researchers at the University of Minnesota as well. The very fact that you had twin siblings separated at birth bearing the same name, both 6 feet tall and weighing exactly 180 pounds is pretty incredible. But theres more.,The Other Minnesota Twins,In her book

9、Entwined Lives, Nancy Segal lists the following shared characteristics: As youngsters, each Jim had a dog named Toy” Each Jim had married twice - the first wives were both called Linda and the second were both called Betty“ One Jim had named his son James Allan and the other Jim had named his son Ja

10、mes Alan“ Each twin had driven his light-blue Chevrolet to Pas Grille beach in Florida for family vacations,The Other Minnesota Twins,Both Jims smoked Salem cigarettes and drank Miller Lite beer Both Jims had at one time held part-time posts as sheriffs Both were fingernail biters and suffered from

11、migraine headaches Each Jim enjoyed leaving love notes to his wife throughout the house Of course, before you start thinking about science fiction movies with pod people, the Jims, like other identical twins, are not carbon copies of each other. Some obvious differences were discovered during their

12、participation in the Minnesota Study of Twins Reared Apart, including: Each styled his hair differently One Jim more clearly conveyed himself through speech, while the other was better suited to writing While both Jims had been married twice, one Jim had taken vows with a third wife called Sandy,Ide

13、ntical Twins, Raised Apart,While not all as eerily similar as the Jim twins, many more instances of uncanny likenesses can be found among twins who were raised apart. The CBS news show 48 Hours interviewed five sets of identical twins who were raised apart, including the following: Also known as the

14、 giggle twins because they laugh and fold their arms the same way, Barbara Herbert and Daphne Goodship spent the first four decades of their lives apart. In the time following their reunion, theyve discovered some remarkable parallels in their lives - both had miscarriages followed by the birth of t

15、wo boys and then one girl. Identical twins Tom Patterson and Steve Tazumi had very different upbringings. Raised in a Christian family by two janitors in rural Kansas, Tom still managed to choose the same career as his brother. Steve, who lives in Philadelphia, was raised in a Buddhist household. Bo

16、th men own body building gyms.,Identical Twins, Raised Apart,Debbie Mehlman and Sharon Poset were also raised by families of different faiths. But nature versus nurture prevails in some interesting ways with these women. They both have the unusual habit of crossing their eyes when they get excited. The Minnesota study even included a set of triplets. Although raised separately, Bobby Shafran, David Kellman and Eddy Galland shared similar personalities. According to the book Entwined Lives, all were described as, inte