Allen and andrew have the same biological parents. why do they not resemble either of their parents?

Follow the directions for self-quiz question 8, draw it, by labeling the appropriate structures with these terms, drawing lines or brackets as needed: chromosome (label as replicated or unreplicated), centromere, kinetochore, sister chromatids, nonsister chromatids, homologous pair, homologs, chiasma, sister chromatid, cohesion