In women, hair loss usually begins at menopause. Although hair loss in females normally occurs after the age of 50 or even later when it does not follow events like pregnancy, chronic illness, crash diets, and stress among others, there has been rare cases reported, in which hair loss affects women as young as 15 or 16. However, unlike with men, hair loss in women typically begins later and is generally not to the full-head state that is generally seen in men.
Balding is genetic and hereditary, and it's thereby logical to think that by looking at family members can be helpful in determining the fate of one's hairline. Sometime it is the case that grandson and maternal grandfather will end up with the similar hairlines, but it's not that foolproof, not the ultimate reference point it's treated as, so better not to consider it at all when wondering if the baldness gene is one you have inherited. Genetic hair loss affects both men and women equally.