There are more twins conceived today than there have been since the 1980s. “One in 30 babies born in 2009 was a twin (a 76% increase since 1980)” (Source Goldman, L. Web). Twins are born in different varieties. They can be fraternal or they can be identical. Identical twins can both be brothers or both sisters. If they are sister and brother they are said to be fraternal. Fraternal twins are twins who do not look alike. Another term for fraternal twins is dizygotic. “...the mother contributes two eggs which are each fertilized in the uterus by two different sperm from the father” (Baby2see, Web source). Identical twins are genetically identical. Another term for identical twins is monozygotic. "...an egg (zygote) from the mother is fertilized by a sperm from the father, and then very early in development the embryo divides and two fetuses grow" (Baby2see, Web source). “Identical twins are always of the same species genus, except in extremely rare cases of chromosomal defect” (Prindle Fierro, source P. Web.) Whenever you see identical twins, they are boy/boy or girl/girl. You rarely see identical twins that they are girl/boy. Many people believe that identical twins are similar in every way. “Identical twins were long believed to be identical to a ridiculous degree. In ancient German folklore, identical twins were said to be the same number of hairs on the head, although no mathematician is cited as having done the counting! However, everyone believed that such a thing was possible, and these beliefs continue to persist today” (Gaddis, Vincent & Margaret, 1972 pp. 11). ) It would be surprising if someone took time out of their day just to count whether twins had the same to... middle of paper... win children twenty-five days apart. Similar twins have also been reported in Bengal, born forty-five days apart. An Australian mother has given birth to her twins who were born fifty-six days apart. However, the record number of days between births appears to have been recorded in 1846 in Strasbourg, France, with an interval of 137 days. On April 30, a baby was born, but the twin did not appear until September 13” (Gaddis, Vincent & Margaret, 1972 (pp. 35-36). It is possible for pregnant women to lose a twin in a miscarriage but still carry the second child to term without any harm resulting. This happened quite frequently. “It is not known whether all these twins born apart were identical or fraternal carried in one womb” (Gaddis, Vincent & Margaret, 1972 (pp. 35- 36). Twins are formed in various ways.