Fraternal twins are two siblings who were born at the same time, but they do not share a common placenta. This means that each twin has their own separate sac and amniotic fluid within the womb. Fraternal twins can be either male or female and occur when two eggs are released during ovulation and fertilized by sperm. The likelihood of having fraternal twins is higher if there is a family history of multiple births, as it suggests that the mother may have a condition called hyperovulation.