Now! Later. No, right now! Maybe in a bit.

Procrastination and impulsivity are both bad habits. They cause problems in school, at work, in life. But psychologically, they would seem to have little in common. Impulsivity, after all, is all about now—wanting and needing something immediately, urgently—and not waiting for later. Later is the province of procrastinators, who will happily delay until tomorrow what could—or should—be done today.

Yet these two character traits do coexist, and that has long puzzled psychological scientists. Why would those who intentionally but irrationally put things off, who don’t seem pressured by time—why would these same people also tend to make rash decisions, without thought or planning? Procrastination and impulsivity are the odd couple of the human mind.

A team of researchers at the University of Colorado in Boulder, headed by Daniel Gustavson, decided to explore this riddle. They were interested in knowing why, from an evolutionary point of view, a trait like procrastination would even exist. Impulsivity makes sense, because early humans needed to act quickly to survive. But there was little need for deliberate, long-range planning, and indeed too much delay could be hazardous. So how was procrastination, as a trait, passed on, from generation to generation, if it was maladaptive?

The Colorado scientists speculate that procrastination may have appeared as a by-product of the more basic and adaptive trait, impulsivity. In the modern world, long-term goals are far more important than immediate survival needs, yet our impulsive tendencies remain firmly ingrained. We keep getting distracted by immediate temptations, with the result that we fail to attend to other, more meaningful goals. In short, we procrastinate, and not only that, we evolved to be procrastinators.

That’s the theory at least, and here’s how Gustavson and the others tested it. They recruited same sex twins, some identical and some fraternal, from on ongoing twin study, and had them complete various questionnaires. One assessed their tendency to procrastinate; another, their impulsivity and lack of foresight. A third—very important—tallied their failures at goal management, the tendency to forget things, not pay attention, and otherwise slip up in everyday tasks. This was a crucial measurement because the scientists suspected that impulsivity and procrastination might both be linked to goal management ability and its failures—in the sense that both delays and rash actions can sabotage goals.

They tested this idea by comparing identical and fraternal twins on these measures. Since identical twins share all their genes and fraternal twins share only half, the scientists wanted to see the extent to which identical twins are more alike than fraternal twins.

The results, to appear soon in the journal Psychological Science, indicate that procrastination and impulsivity are both moderately heritable, and indeed are strongly linked genetically. In fact, the two traits are inseparable at the genetic level. What’s more, this shared genetic variation overlaps with variation in goal management ability—supporting the idea that both impulsivity and procrastination are linked to the inability to prioritize goals and pursue those goals effectively.

These results are robust but open to interpretation. It’s possible, for example, that impulsivity might be a by-product of procrastination, instead of the other way around. It’s easy to see how delaying and delaying could, when time finally runs out, trigger fast and rash action. The jury’s still out, but that’s an explanation that will ring true for anyone who has ever dawdled, then panicked, on deadline.

Follow Wray Herbert’s reporting in The Huffington Post and on Twitter at @wrayherbert.