Hemophilia is a sex-linked recessive disorder as per the center for disease control. The abnormal gene responsible for hemophilia is carried on the X chromosome. As the below hemophilia pedigree chart suggests, the mother is the one who passes the hemophilia gene. However, the father's sperm determines if the child will be a boy or a girl. It is not the "fault" of one parent since both parents contribute to the outcome. As the diagram illustrates, hemophilia A and hemophilia B are inherited in an X-linked recessive pattern. The genes associated with these conditions are located on the X chromosome, one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition.
