K i myself being a Twin.. I thght i'l share sum info bout twins...
1st of all There are 2 types of twins 1) Identical 2) Fraternal
Identical Twins happen when a single fertilized egg splits usually one to fourteen days after conception. Identical twins are genetically alike.They have the same chromosomes and usually have a lot of the same physical features but are not totally the same. Each twin is an individual and has different traits of his own. Identical twins are the same sex, the same blood type and have the same hair and eye, color, same nose, ear and lip shapes.
The identical birth rate is approximately 4/1000 births and is thought to be an accident of nature.Chances of having two sets of identical twins is one in 70,000.
Identical twins spend a lot of time together and are usually each other's best friend. Although they like other people, their twin is the person they usually choose to be with, especially when they are young. They do not like to be apart. Identicals usually have their own private language and have the ability to do the same in the same activities. They also enjoy each others company because they usually have the same interests.
Identical twins usually care for one another more deeply than fraternals. This is because of the special bond between them that grew while they were inside their mother. After age 9 or 10, identicals usually choose to form their own identities.
Fraternal Twins are the most common type of twins. They are the result of the union of two eggs and two sperm. They may not look alike and can be different sexes. Fraternal twins can be conceived at separate times and can have different fathers.The tendency to conceive fraternal twins seems to be heredity. Some studies show higher incidence where there is a history of twins on the mothers' side of the family. About two-thirds of all twins are fraternal.
Opposite-sex twins make up one-third of the twin population, about one in 240 births. Boy/girl twins develop as differently as single birth children from the time of conception. Boys are usually heavier and longer than girls both before and after birth. Growth is faster in boys than girls until about 7 months of age, at which time females begin to grow faster until about the age of 4 years. Girls, on the average, tend to sit, crawl and walk earlier than boys. Boys show earlier visual skills while girls show greater talking skills.
While Fraternal twins do not usually develop the closeness and psychological interdependence that identical twins do, they do develop that " special bond" that all twins are known for.