Jon, please contact Chet Berlin, MD at the Hershey Medical Center in Hershey,
PA. He's done quite a lot of research on this, and spoke at the 1995 ILCA
conference on the topic.
Also, La Leche League has good references and an excellent fact sheet.

And speaking of perkiness - what's the big deal about body parts that stick
out? Other parts that are prominent (like big noses) are seen as a drawback.
Some parts that become prominent at the wrong time are embarrasing to their
owners. I'm in favor of the law of gravity.

Linda Smith