• Question: How is gender of a baby determined?

    Asked by gigi123 to David, Helen, Ian, rhysphillips, Sarah on 22 Jun 2011.
    • Photo: Sarah Cook

      Sarah Cook answered on 21 Jun 2011:

      Chromosomes, XX is a girl and XY is a boy. The 1st X comes from the mother and whether its an X or Y is determind by the father. Hence, your dad decides if you are a boy or a girl – its random he can’t actually influence it

    • Photo: Helen Fletcher

      Helen Fletcher answered on 22 Jun 2011:

      This XX / XY system, which is how it works in humans, is also found in other mammals and some insects. But other animals use other systems, such as grasshoppers, in which there is no Y chromosome, so females have XX and males just have one X and nothing else. In ants and bees, unfertilised eggs become males and fertilised eggs become females. Sex can even be determined by the environment rather than genetics: in alligators it depends what temperature the egg is incubated at. Just to confuse things, snails can start out male and later become female.

    • Photo: Rhys Phillips

      Rhys Phillips answered on 22 Jun 2011:

      The chromosomes it inherits from its parents.

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