Sheldon assigned certain personality traits to each of the three soma-types: mesomorphs were hard-working, aggressive, and extroverted, but not necessarily smart; endomorphs were relaxed (almost lazy), sociable people; ectomorphs were likely to be introverted, sensitive, and most often found with their head in a book. According to Sheldon, the mesomorph was most likely to wind up behind bars.

Sheldon's theory didn't pan out — after all, criminals come in all shapes and sizes. His theories have been debunked as an attempt to prove what he expected to see (in other words, he judged people by their appearance and viewed their body language from that clouded perspective).

The lesson to be learned here is that even educated people make judgments (and mistakes) about how body types relate to behavior. The fallout from this includes hurt feelings, misunderstandings, and unwarranted advantages and disadvantages (depending on one's body type). You can't ignore the body sending nonverbal cues, but you can learn to separate the body language from the body type. In other words, do your best to evaluate and judge the gestures instead of the physique behind them.