Apparently, Swedish sperm donors are more stable, mature and have better social skills than the average Swedish man, according to the results of a new study.

The study suggested that sperm donors score better in aptitude tests on responsibility, confidence and self-acceptance, when compared to non-donors. The study was conducted at Linköping University in central Sweden.

The findings have been published in the British Journal of Obstetrics and Gynaecology. The study focused on 115 men who donated sperm at clinics in Sweden between 2005 and 2008, comparing them with men of similar age who did not attempt to donate sperm.

The men who are accepted for the program were all in the normal range of character and also demonstrated a mature personality and a stable character, said the study's main author Gunilla Sydsjö in an email to Reuters Health.

Sweden was the first country to pass a non-anonymous law that allowed children to contact the sperm donor, if they so wanted to. Furthermore, in Sweden men are only allowed to volunteer for donation; in the U.S., not only are donors allowed to remain anonymous, they can also be paid.

In addition to improved scores on aptitude tests, differences were also found between single and married men making deposits. The former tended to be more pessimistic and passive. The study also showed that 43 percent of Swedish donors were married and 36 percent had children of their own.