Yes the term blue blood comes from the condition of hemophilia, which most of the royal families was known to suffer from. Why did they suffer from it in such great numbers? People have said it was because most of the royal families were so closely related. A royal person could only marry another royal person, so as the generations went on you were lets say keeping it in the family i guess.
Some bleeding disorders are present at birth and are caused by rare inherited disorders. Others are developed during certain illnesses (such as vitamin K deficiency, severe liver disease), or treatments (such as use of anticoagulant drugs or prolonged use of antibiotics). They can include hemophilia and other very rare blood disorders. There are many causes of bleeding disorders, including:
von Willebrand's disease , which is an inherited blood disorder thought to affect between 1% and 2% of the population
Immune system-related diseases, such as allergic reactions to medications, or reactions to an infection
Cancer, such as leukemia, which is a blood cancer
Bone marrow problems
Disseminated intravascular coagulation, which is a condition often associated with child bearing, cancer, or infection, in which the body's clotting system functions abnormally
Pregnancy-associated eclampsia, also known as severe toxicity of pregnancy
Organ transplant rejection o Hemophilia A and B , which are inherited blood disorders
Exposure to snake venom
Antibodies, a type of immune system protein, that destroy blood clotting factors
Medicines, such as aspirin, heparin, warfarin, and drugs used to break up blood clots
Congenital bleeding disorders are very rare, and with the exception of hemophilia and von Willebrand disease, education about them has not been a priority of the medical community. Most have only been discovered and described in the past few decades.