Differences among human beings

   Recently, an idea struck me that similarity of physical appearances in families are recognized more easily than that of mental structures. I happen to be very good at picking up a mom and daughter relationship in a street, just by glancing at breifly. Of course, it was merely a simple observation that everyone else could do it. But whlile talking about matters relating to natures, characters, preferences, talents, and personalities among falily members, that would be a totally different story. Although invisible stuffs are pretty hard to be intuitively coded into a certain pattern, it is very rare to spot some kind of familiy ties in a conscious and cognitive level after grown up. 

   Maybe this is far beyond my scope of common senses. And this subject would be fallen into a category of advanced studies for psychological specialists.

   An absolute thing for sure is that combinations of internal stuffs are almost infinite.