Final answer:
Chromosome abnormalities in humans increase with the parent's age, especially due to nondisjunction during meiosis which can lead to conditions like Down Syndrome.
Step-by-step explanation:
Abnormalities in chromosome number in humans rise with an increase in the age of either parent. Chromosome abnormalities, such as the duplication or loss of entire chromosomes, or changes in the number of complete sets of chromosomes, are mainly driven by nondisjunction. This process, occurring during meiosis, involves the failure of homologous chromosomes or sister chromatids to separate properly. The risk of nondisjunction, which can lead to conditions like Down Syndrome, is notably higher as the parental age increases. This correlation is especially pertinent with increasing maternal age, as the incidence of giving birth to children with trisomy, such as trisomy 21, is higher in older women.