Identical twins arise from a single fertilized egg that for some reason split itself in two. Identical twins have exactly the same genetic make-up.
Fraternal twins arise from two separate eggs. Sometimes both of a woman's ovaries will produce an egg cell at the same time. Each of these is fertilized by a separate sperm cell (of which there are always plenty) so they have different genetic make-up. They may share the same womb and be born at the same time but are no more closely related than true brothers.
Identical twins come from one egg and one sperm. Fraternal twins come from two eggs and two sperm.
There is no precise percentage of fraternal or identical twins but it is estimated that 2/3 of all twins are fraternal where as 1/3 of twins are identical.
The girl and boy twins are fraternal, meaning they are not identical.
Identical twins are formed from a single egg that splits into two. Fraternal twins are formed from two separate eggs that are both separately fertilized. So identical twins have identical DNA, and fraternal twins do not.
If two (or more) eggs are fertilised and develop together you will get fraternal twins. Identical twins are the result of a single fertilised egg dividing into two embryos.
Fraternal twins are more popular.
(Person that asked the question)-Once twins are born, and old enough to determine whether they are identical or fraternal, how do you know if they are identical, or just fraternal twins that look identical? I was just curious.
identical twins are from the same egg cell that split, but ferternal twins are from 2 entirely different fertilized egg cells. Thus identical look the same and ferternal can look entirely different.
Female twins that are not identical are called fraternal twins. Fraternal twins occur when two separate eggs are fertilized by two separate sperm. Maternal twins refer to twins that share the same mother but can include both identical and fraternal twins.
Identical twins are formed from a single egg that splits into two. Fraternal twins are formed from two separate eggs that are both separately fertilized. So identical twins have identical DNA, and fraternal twins do not.
They are twins!
Identical twins come from the same fertilized egg; fraternal twins come from 2 fertilized eggs.