There's also considerable variation in size involving persons. Long lasting breast expansion in the course of puberty is due to estrogens in conjunction with the growth hormone. Woman human beings are the one mammals that permanently build breasts at puberty; all other mammals establish their mammary tissue over the latter https://grok.com/share/c2hhcmQtMw%3D%3D_5ad6450c-533d-442c-a09c-9f7bce1babfb