Fava bean disease is a sex chromosome recessive inheritance, meaning that it develops in women only if both pairs of X sex chromosomes carry the gene for the disease, and in men, there is only one X sex chromosome, so as soon as this X chromosome is abnormal, the disease develops.

Females with only one abnormal X chromosome have no symptoms, but the boys they give birth to will develop the disease if they get this abnormal X chromosome. That is why the disease is more prevalent in males, while their parents may be asymptomatic. It is common for both parents to be free of the disease, but for the mother to carry a chromosome with the disease, in which case half of the boys born will have fava bean disease; half of the girls born will be normal, but half of them will have a recessive gene like their mothers.