At the 1988 Seoul Olympics, the R.O.C. team included a pair of 25-year-old twins as table tennis partners: Chi Chin-shuei and Chi Chin-lung. They began playing at eleven and have shared a great sense for each other's movements. Chin-lung says that from the first time they played together until now he would always know what shot his brother would hit. Their abilities are about the same.

Chang Min-yi of Taipei believes that if she summons up her energy she can send a message to her sister teaching in the mountains of Nantou to give her a call.

Lu Ssu-she and Lu Ssu-fen this year began the second grade. On almost every exam their errors are similar, as are errors in writing characters. What's interesting is that they don't sit together during tests.

These hard-to-explain coincidences are what make the topic of twins so much fun.

Most people know that there are two kinds of twins: identical (where the egg splits after accepting the sperm, so that the genetic makeup is identical), and fraternal (where two different eggs are fertilized by two different sperm). Lately a third type has been discovered: "semiidentical twins," where two sperm attach to one egg as it is dividing, giving more similarities than fraternal twins would get.

It is even possible for twins to have two different fathers. One woman gave birth to racially mixed twins after two eggs were fertilized separately by fathers of two different races.

According to statistics, there are 45 million sets of twins in the world. The rate of twins is lower in Asian countries (one set per 100 births in the Taiwan area, one per 103 in Japan) than in the West (one per 83 in the U.S., and one per 79 in Western Europe).

Chen Chien-jen, Professor at the Graduate School of Public Health at National Taiwan University, says that one reason for the discrepancy is that women in the West give birth much later (about five years on average for the first birth) than women in the Orient. Because the reproductive secretions are more confused as a woman gets older, the chances of twins go up, peaking at 35 to 40 years old.

Genetics is another factor. A study of 4,000 Mormon mothers who were themselves twins showed a very high rate of one set per 58 births. Taking fertility drugs or getting pregnant after coming off birth control bills also both increase the chances for twins.

Even diet can be a factor. The Yoruba tribe in Africa has 18 million people--900,000 of whom are twins. This has been connected to the chemical effects of consuming yams--a Yoruba staple--on the reproductive system of the woman.

Twins have their own organizations and lore. One town in the state of Ohio in the U.S. became famous for a set of its twins, and came to be called "Twinsburg." It is now a meeting place for twins every summer and site of Twins magazine.

Last year, the Parents of Twins Friendship Association was formed in the R.O.C. under Taiwan University Public Health Associate Professor Chang Chueh. In research since 1985 on twins she has discovered that parents of twins face many similar problems raising them. So she formed the group and declared November 11 as "Twins Day" to encourage parents of twins to share experiences and help each other out. About two hundred couples have already joined.

For parents of twins the first concern is health. The rate of premature births for twins is 80 percent; many are born underweight. Many organs, such as the lungs or optic nerves, may not have properly formed at birth. They require a lot of care.

Because the capacity of the womb and that of the mother to supply nourishment are limited, there can be competition between the twins while still in the womb. This causes most newly born twins to share a very common feature, namely that one of the two has not-so-good health.

Mother of twins Chen Ju-ping says that her older twin had relatively poor health. As a result, he relied more on his mother, which caused some jealousy on the part of the younger brother. "Twins are possibly closer than ordinary siblings; but sometimes you must be careful. The parents don't want to favor the weaker one and ignore the other."

At the Hsiu-lang Primary School in Yung-ho, a suburb of Taipei, there are 15,000 students, including 61 sets of twins, numerically and proportionally the highest in the nation. The school always lets parents decide whether or not to put the twins in the same class. Recently the school did some research to determine whether those together or those separated did better.

Teacher Lin Mei-hui noted that competition between twins can be tough, and that the one on the short may get ribbed for it. "Twins in the same group most easily become competitive," she says, and suggests there is no harm in putting the twins in different schools or classes, or letting them make different circles of friends. This could avoid harmful comparisons.

Chang Chueh agrees. She suggests children be raised as individuals, wearing different clothes which they choose themselves, or taking up different interests.

The most difficult thing to explain about twins is the sometimes eerie "sixth sense" that allows them to communicate.

Five years ago on a day in November, farmer Lin Chang-keng was out tending his fields when he was struck by a sharp pain in the chest like a powerful electric shock. Shortly after, on the same day, he called his twin brother's residence only to be told by his nephew: "Father just died of a heart attack."

These kinds of "ESP" usually occur at great events: births, deaths, and severe pain. But as for how it happens, no one can say.

A British scientist named Galten in the nineteenth century was the first to systematically study twins. Since identical twins are genetically alike, but have different upbringings, they provide excellent opportunities to compare "nature vs. nurture" arguments.

From a scientific point of view, twins may share certain similarities as they develop. They might need medical treatment about the same time, for the same problems. Cavities will appear in the same teeth at the same time. Girls may begin menstruating at the same time. Professor Wu Kwang-tong suggests that similar physical problems may occur close together because physical development is closely related to genetics.

At the same time, however, Professor Wu also emphasizes the importance of environment. In dental health, for example, parental teaching in the ways of dental hygiene or copying of one twin by the other may be the actual cause of surprisingly similar health problems.

The birth of twins is a double miracle, and the beginning of two lifetimes sharing main roles in a constantly evolving mystery. In an age when people are searching for identity, perhaps twins have a leg up in knowing themselves.

[Picture Caption]

Hsiu-lang Primary School in Yung-ho boasts 61 sets of twins.

Grandmother Cheng says that there is a set of twins every generation in her family. Pictured are the two sets on Taiwan. The picture on the left is of Cheng Chih (left) and Cheng Jen, born in Hong Kong forty years ago. The picture on the right shows Cheng Chih's Pai-tang (left) and Pai-ti (right) at age three. The picture of the four, taken in October this year, has Pai-tang with Dad and Pai-ti with Uncle. Compared with old times, do they look different now? (photos left and right courtesy of Chen Ju-ping).

Ssu-chin (right) and Ssu-chieh are lively, adorable twin sisters, and have therefore appeared in several TV ads.

Mother has to prepare similar clothing and teacher has to give similar amounts of work in order to prevent subtle sibling jealousy.

Twins share the same face; and as they look into the lens, it seems there is a meeting of minds as well.

Wang Hai-ning (right) saved his brother's life ten years ago by giving him a kidney, bringing the two brothers even closer together.

Grandmother Cheng says that there is a set of twins every generation in her family. Pictured are the two sets on Taiwan. The picture on the left is of Cheng Chih （left） and Cheng Jen, born in Hong Kong forty years ago.

The picture of the four, taken in October this year, has Pai-tang with Dad and Pai-ti with Uncle. Compared with old times, do they look different now? （photos left and right courtesy of Chen Ju-ping）.

The picture on the right shows Cheng Chih's Pai-tang （left） and Pai-ti （right） at age three.

Ssu-chin （right） and Ssu-chieh are lively, adorable twin sisters, and have therefore appeared in several TV ads.

Mother has to prepare similar clothing and teacher has to give similar amounts of work in order to prevent subtle sibling jealousy.

Twins share the same face; and as they look into the lens, it seems there is a meeting of minds as well.

Wang Hai-ning （right） saved his brother's life ten years ago by giving him a kidney, bringing the two brothers even closer together.