How fraternal twins formed?

Answer 1

Fraternal twins, and most other multiple births, occur when multiple eggs are released during gestation and fertilized. Each fetus is contained within a separate placenta. Although they have the same parents, they will not have identical DNA, as any of the combinations of the DNA pairs are possible. Fraternal twins may develop into either sex, depending on whether the X or Y chromosome remains dominant. Although they can sometimes look similar due to dominant parental genes, it is more likely for them to look and develop as separate individuals as different as other separately born siblings. That means one could be tall and the other short, one skinny and one fat, one might resemble dad and the other mom, different blood types, etc.