These twins are referred to as identical since the sequence of the twins' DNA is identical. Identical twins must be of the same sex. However, identical twins tend to be very similar for traits such as hair color, hair texture, eye color, height, and weight. When two eggs are independently fertilized by two sperm cells, fraternal or dizygous twins result. Fraternal twins do not have identical DNA but will have half of their DNA in common, just like siblings of the same parents that are born at different times.
Fraternal twins can either be of the same sex or different sex.
My physician already determined that the twins are fraternal. Unless a DNA or other blood test was performed, it is difficult to definitively determine if twins are fraternal. This is a common cause of incorrect zygosity classification. A DNA test is the easiest way to resolve this potential confusion. My physician already determined that the twins are identical.