Meiosis

The 46 chromosomes in a human cell consist of 23 pairs - one set inherited from each parent. When cells divide to make egg or sperm cells they receive only one chromosome from each of the pairs. This means the new cells usually end up with 23 chromosomes. When an egg and sperm join together at fertilisation, the new cell they make will have the normal number of 46 chromosomes again - the complete set needed for a making a new person.