Part 1 of Essay
are rare in humans with twins as being the most common form of this event. can arise in many different combinations of ways but the probability of giving birth to more than one child remains fairly constant when compared to the entire human race. The chances of can also vary from race and genetic background. Scientis ....

Part 2 of Essay
.... a single pregnancy, to survive in medical history were the Dionne quintuplets. The use of drugs that treat female sterility, or fertility drugs, may increase the chances of giving birth to multiple children. These drugs cause the ovaries to release an egg once a month but in some cases they release more than one egg, sometimes releasing several at a time, increasing the chances of a multiple birth. The drug clomiphene citrate is one of the most widely taken fertility drug and has resulted in the birth of twin ....