Blood is one of the most easily donated tissues. According to the American Red Cross, a person in good health who weights at least 110 pounds (50 kilograms) can donate blood every 56 days. Platelets may be donated every seven days up to 24 times per year. Plasma may be donated every 28 days up to 13 times per year.

No child can acquire a gene, and consequently a blood grouping, if it is not possessed by either parent.