Testosterone controls male traits, such as muscle mass and body hair. Estrogen controls female traits, including the growth of breasts.
Breast enlargement is usually caused by an imbalance of estrogen (female hormone) and testosterone (male hormone). Males have both types of hormones in.
Breast enlargement with increased breast gland tissue in men is called gynecomastia. (male sex hormones), they also produce the female hormone estrogen.