Chromosomes are what the mother and father donate to the fetus in order to compose your basic genetics
The father gives half which is 25 and the mother gives 23
The reason for this is when a baby is being created it is given a gender. That gender is either boy or girl the boy has an added chromosome at the near middle of gestation and the girl lacks that last chromosome so thats why the father gives more chromosomes than the mother.
Hope this helps.