I suspect that these &quot;extra smells&quot; are subjective, and that there&#x27;s no chemical basis for any of them.<p>When it talks about how brothers and sisters can&#x27;t sit too close together because &quot;their smells would mingle&quot;, they could have easily substituted in the words &quot;auras&quot; or &quot;mojo&quot;, and it would have the same semantic meaning.<p>It&#x27;s more interesting to speculate on why they would develop these subjective values in the first place, than it is to wonder why they&#x27;ve confused those values with actual odors.