There exists also considerable variation in sizing involving men and women. Long-lasting breast development for the duration of puberty is caused by estrogens together with The expansion hormone. Woman humans are the only mammals that permanently create breasts at puberty; all other mammals create their mammary tissue in the latter https://grok.com/share/c2hhcmQtMw%3D%3D_5ad6450c-533d-442c-a09c-9f7bce1babfb