The true scientific term for bitch tits is in fact Gynecomastia.

While it is a well known fact that bitch tits can result from the use of modern steroids, gynecomastia has actually been around for a long time. It has been found that the statues of Pharaoh Seti I have enlarged breasts suggesting that the Pharaoh may have had bitch tits.

Also, there are four types of Gynecomastia:
Type 1: Benign adolescent breast hypertrophy or pubertal gynecomastia. Could be found in up to 60-70% of males. Not serious at all (except I imagine it would be a bit damaging to one's self-esteem)

Type 2: A general increase in size of breasts. Not painful. Possibly resulting from the use of a specific drug, from family history, weight change, illness etc.

Type 3: General Obesity Simulating Gynecomastia.

Type 4: Pectoral Muscle Hypertrophy.

Just a little observation: I believe the term bitch tits was made popular by the movie Fight Club in which Bob, a friend of the main character, grew enormous bitch tits as a result of having his testicles removed