During fertilization, the encounter of gametes results in the fusion of their nuclei. The nucleus of the egg cell thus formed is therefore a mixture of the two nuclei.
So the parent will only give half of his chromosomes, so the child will have 50% of his chromosomes that resemble each of his parents.
Another factor that must be mentioned is the genetic recombination between the chromosomes that occurs during meiosis of the reproductive cells. Thus, this will give a heterogeneous chromosome resulting from recombination of the two chromosomes of each of its parents, and the child will have a unique combination chromosome but keeping the alleles of both parents.
