Can fraternal twins be the same gender?

Two girl twins can be either identical or fraternal (monozygotic or dizygotic). Two boy twins can be either identical or fraternal (monozygotic or dizygotic). A set of boy/girl twins can only be fraternal (dizygotic). Boy/girl twins cannot be identical (monozygotic). read more

Fraternal twins just happen to inhabit the same womb at the same time, instead of sequentially, because fraternal twins are the result of two eggs being released (instead of one that splits). Gender is determined at fertilization, so there's a 50/50 chance that fraternal twins will be the same sex. read more

About 1/2 of fraternal are mixed gender, second most common are girl/girl twins just over a quarter, then boy/boy with just under 25% in actual practice just due to the natural gender gap. read more