There can be two types of twins 1) Fraternal 2) Identical. Fraternal twins develop from two different eggs. Most twins are fraternal . And due to untimely abrupt and early pregnancy, many times the same egg splits and produces identical twins. What are the reasons ? 1. Statistics show that in the last few years, the birth rate of twins has increased by 7 Physicians believe that the main cause of multiple ovulation is the drug that is used to treat infertility, resulting in the birth of twins. 2. In the case of a test-tube baby, multiple embryos are transferred to the mother's womb , in which case there is a possibility of giving birth to twins. 3. Physicians think that pregnancy is a big reason in old age 4. Hereditary causes.