Here's why:
* Sex cells are haploid: This means they contain half the number of chromosomes found in a normal body cell (somatic cell). For example, humans have 46 chromosomes in their body cells, but their sex cells have only 23 chromosomes.
* Fertilization: When a sperm cell fertilizes an egg cell, the two haploid sets of chromosomes combine, resulting in a diploid zygote. This zygote now has the full complement of chromosomes, which is the same number as the parents.
In summary: Offspring receive half their chromosomes from their mother (through the egg) and half from their father (through the sperm), resulting in a complete set of chromosomes.
