Human beings have 23 pairs(46) of chromosomes (22 pairs of autosomes +1 pair(2) of sex chromosomes). A male has one X chromosome and one Y chromosome whereas a female has XX chromosomes. The sex of a child depends on the two conditions which take place during fertilisation. The two conditions are given below:
If a sperm carrying an X chromosome fertilises an ovum which carries an X chromosome, then the child born will be a girl.
If a sperm carrying a Y chromosome fertilises an ovum which carries an X chromosome, then the child born will be a boy.
