Gynecomastia may be a condition that creates breast tissue swell in boys and men. It will happen once the balance of 2 hormones in your body is thrown off. though breasts don’t develop in men the manner they are doing in girls, all boys square measure born with atiny low quantity of breast tissue. Boys’ bodies largely create a endocrine referred to as androgenic hormone, that guides their sexual growth throughout time of life. however males additionally create some {estrogen|oestrogen|steroid endocrine|steroid|sex hormone} -- the hormone that steers sexual growth in women. once a boy goes through time of life, or once associate degree older man’s body makes less androgenic hormone, the balance of the 2 hormones changes. typically once that happens, the next proportion of steroid causes male breast tissue to swell. regarding half adolescent boys and as several as simple fraction of men older than fifty can have this to a point.