Answer:
Causes of sterility include diabetes, obesity, thyroid disorders, adrenal hyperplasia, mumps orchitis, and others - among physical causes. There are also psychological factors (though not as prominent, percentage-wise), including anxiety disorders.
Additional causes, in women, include polysystic ovarian disease, Frolich's syndrome, high vaginal acidity, and structural abnormalities in the vagina, cervix, uterus, fallopian tubes and ovaries.