To do natural breasts right, you either need a lot of refined sculpting and morphs, or a high end soft body simulation. 

Also, eith breasts, what looks good nude is a nightmare to support with clothing (especially various conversion snd fitting utilities), and what works for clothing is too oversimplified for nudes.

Similar happens with butts, full figured or any other figure with more fleshy parts.. and even muscle behavior when bending limbs. This is still a domain of much higher end 3d programs.

Quick example. http://www.syflex.biz/tut_skin01.html

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Renderosity Store  Personal nick: Conniekat8
Hi, my name is "No, Bad Kitteh, NOO", what's yours?