They don't like tedium, nondeterminism, or most of the fussy, boring, ill-defined little tasks that go with maintaining a normal existence. Accordingly, they tend to be careful and orderly in their intellectual lives and chaotic elsewhere. Their code will be beautiful, even if their desks are buried in 3 feet of crap. Hackers are generally only very weakly motivated by conventional rewards such as social approval or money. They tend to be attracted by challenges and excited by interesting toys, and to judge the interest of work or other activities in terms of the challenges offered and the toys they get to play with.
Hackers have relatively little ability to identify emotionally with other people.
Unsurprisingly, hackers also tend towards self-absorption, intellectual arrogance, and impatience with people and tasks perceived to be wasting their time. This bias often contributes to weakness in communication skills. Hackers tend to be especially poor at confrontation and negotiation. As in society at large, the intensity and duration of these debates is usually inversely proportional to the number of objective, factual arguments available to buttress any position. As a result of all the above traits, many hackers have difficulty maintaining stable relationships.