• Question: Why can't there be conjoined twins that are different sexes

    Asked by poplol123 to Alberto, Chris, Emmanuel, Jennie, Michelle on 19 Jun 2013.
    • Photo: Chris Whittle

      Chris Whittle answered on 19 Jun 2013:

      Conjoined twins are always from the same egg, and so they will always be identical. This is because the egg does not split properly, leaving the twins joined in some way. Non-identical twins (like a boy and a girl) come from two different eggs.

    • Photo: Michelle Taylor

      Michelle Taylor answered on 20 Jun 2013:

      Chris is spot on there! They share the same chromosomes – wiggly bits inside of cells that contain genes. In humans male babies have an X and Y shaped chromosome, girls have an X and X but twins that develop from the same egg have the same as each other.

    • Photo: Emmanuel Amabebe

      Emmanuel Amabebe answered on 20 Jun 2013:

      conjoined twins usually develop from thesame fertilized egg (ovum) that fail to divide completely during embryonic development inside the uterus(womb), while unidentical twins e.g. twins of different sexes develop from two separate eggs (ova) fertilized by two separate sperm cells. So there would hardly be conjoined twins of different sexes.

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