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Old 06-23-2016, 04:54 PM
Trinopus Trinopus is offline
Join Date: Dec 2002
Location: San Diego, CA
Posts: 22,852
I'm not sure of this, so please, someone, help me out... But wouldn't it be polygenetic? (As opposed to blue eyes, which are brought out by a single gene.) Like skin color: there isn't just one gene for "dark skin," but several genes, so you can get gradations of color.

Another argument for it being polygenetic is that mothers and daughters can differ very widely in breast size. There is some heritable correlation -- larger mothers tend to have larger daughters -- but there are so many exceptions that it can't be a really simple genetic heritage.

Or maybe I'm wrong...

(ETA: also, diet, including some food additives/contaminants that are so influential, they gave even boys breasts.)