Mom is right; people can’t control when they start their periods. This, more than anything, is what upsets Margaret. Technically speaking, starting one’s period at 14 isn’t all that late—but for Margaret, when her friends are already starting at 11 or 12 years old, having to wait another two years seems like proof that she’ll never fit in. Especially combined with her struggles to find a religion, this deepens Margaret’s feeling of being abnormal.