The first 23rd pairs carry genes for body characters and are called autosomes
The 23rd pair carry genes that determine the sex of a child and are called sex chromosomes
The inheritance of sex chromosomes will determine whether we are a male or female
The sex chromosome in male conprises and « X » and a « Y » chromosome while the sex chromosomes in female comprise two identical X-chromosomes.
Male therefore have the genotype « XY » while female has the genotype « XX »
Male produces two types of sperm in equal ration, 50% carrying the x-chromosome and 50% carriying the y-chromosome. Male are therfore said to be heterogametic because the produce different kinds of gametes
The female produce one kind of egg will all carying the x-chromosomes. They are therfore said to be homogametic
The sex of a child is determine primarily by probabilities or chance and depends on the kind of sperm that fertilises the egg.
If a sperm carrying the x-chromosomes fertiliese the egg, a female child re »sult i.e X(sperm) + X(egg) =XX(female offspring)
If a sperm carrying the Y-chromosomes fertilise the egg(X) a male child will result
Therfore there is an equal probability or chance of producing a male child or a female child
