Children born to parents with blood type A and O may have blood type A or O. The human blood type system is hereditary and this hereditary property is determined by the chromosomes. Human blood type is hereditary, and this hereditary property is determined by chromosomes. 23 pairs of chromosomes are inherited from both the father and the mother, each of which is passed on to the offspring. the inheritance of the ABO blood type system is dominant, and it is controlled by the 3 alleles of A, B and O on chromosome 9. Since each pair of chromosomes can only have 2 of the A, B, and O genes, the two combinations form our common A blood type (AA, Ao), B blood type (BB, Bo), AB blood type (AB), and O blood type (oo). The A and B genes are dominant and the O gene is recessive. In other words, when the A or B gene and the O gene are present at the same time, the blood type is A or B. When the A and B genes are present at the same time, the blood type is AB, and only when both chromosomes have the O gene. Blood type A is AA or Ao, and blood type O is oo, so the child’s blood type must be Ao or oo, i.e., A or O. For more information, please go to the hospital. Please go to the hospital for blood typing.