Twins can be identical boys, identical girls, non-identical boys, non-identical girls or one boy and one girl what are the possible combinations with quadruplats

The possible combination for quadruplets are,

Two pairs of identicals.Three identical and one fraternalTwo identical and two fraternal    

Explanation:

Quadruplets is a multiple birth condition where a women gives birth to four infant at a single pregnancy.

Theoretically quadruplets occurs as a result of four fertilized eggs getting fertilized by four separate sperms.

The following are the possible combinations of Quadruplets,

Two pairs of identicals.Three identical and one fraternal.Two identical and two fraternal.  Two pairs of Identicals includes two identical boys and Two identical girls.Three identical and one fraternal includes Three identical Boys or girls and a single non identical boy or girl.Two identical and two fraternal pair includes two identical boys or two identical girls and Two non identical boys or Two non identical girls.