Because of this, not all sperm are perfect. There are from 40 to 400 million sperm released each time. Healthy sperm can survive 2 to 3 days in the female body. The joining of a live sperm and egg. Fertilization normally takes place in the Fallopian tube leading from the ovary to the uterus.
Fraternal twins are two egg cells fertilized by two sperm cells.
These two individuals are no more alike than any other siblings. Fraternal twins occur because the mother has produced two mature eggs during a single cycle. There is generally some confusion about twins running in a family. The tendency to produce more than one egg per cycle is an inherited trait . This trait is carried by the female, so twins might be predicted if the females on the mother's side of the family have had fraternal twins.