"But the predisposition for chest fat, assuming you're not a giant lardass, is related to estrogen levels no?"
NO
In fact, men are more prone to 'chest fat' than women. Chest fat is not the same as the fibrous fatty tissue that women have. If the fat is 'hard', tender and mostly around the nipple then it is estrogenic tissue. If it's just a lot of subcutaneous fat in your pec area, then it will respond well to plain old dieting. The best way to tell is take a diagonal skinfold measure halfway between your nipple and your armpit. If it's a big fold of skin, then it's time to diet. If it's a small fold of skin and your nipples are swollen and sore, it's time for anti-Es.