There's also substantial variation in size amongst people today. Long-lasting breast expansion during puberty is brought on by estrogens in conjunction with the growth hormone. Feminine human beings are the sole mammals that permanently develop breasts at puberty; all other mammals create their mammary tissue through the latter duration of https://grok.com/share/c2hhcmQtMw%3D%3D_5ad6450c-533d-442c-a09c-9f7bce1babfb