Typically, humans have 46 chromosomes in every cell of their body. Those 46 chromosomes are actually 23 pairs of chromosomes.  A child inherits one set of 23 chromosomes from their father, and one set of 23 chromosomes from their mother. 

In order for an embryo to receive the correct number of chromosomes from each parent, the egg and sperm from the parents must undergo an extra division to go from 46 chromosomes to 23 chromosomes. This special cell division process is called meiosis.  Following meiosis, the egg and the sperm each contain only one copy of each chromosome.When an egg and a sperm fuse at conception, there are 46 chromosomes again.  The embryo has two copies of each chromosome, one from each parent.