The shorter the index finger is compared to the ring finger, the more boisterous he will be, University of Alberta researchers said.
But the same was not true for verbal aggression or hostile behaviours, they told the journal Biological Psychology after studying 300 people's fingers.
The trend is thought to be linked to testosterone exposure in the womb.
It has been known for some time that there is a direct correlation between finger lengths and the amount of the male sex hormone testosterone that a baby is exposed to in the womb.
Other studies looking at finger length ratio have suggested that, in men, a long ring finger and symmetrical hands are an indication of fertility, and that women are more likely to be fertile if they have a longer index finger.
One study found boys with shorter ring fingers tended to be at greatest risk of a heart attack in early adulthood, which was linked to testosterone levels.
In the current study, Dr Peter Hurd and his student Allison Bailey measured the fingers of 300 undergraduates at their university.
Men with the shortest index fingers scored higher on measures of physical aggression than those with longer index fingers, but the study's findings did not apply to women.
He said: "Finger length can tell you a little bit about where personality comes from.
"A large part of our personalities and our traits are determined while we are still in the womb."
But he said finger length should not be used to draw too many conclusions about an individual person.
Professor John Manning from the University of Central Lancashire's department of psychology, who first realised that sex hormone exposure in the womb influences finger length, agreed.