A new study from the good people at Emory University has found that a man's testicle size can determine what kind of father he can be—fathers who have a smaller set of jewels down below tend to be more active fathers in their children's lives. Nuts, right?   

"Our results suggest that the biology of human males reflects a trade-off between mating effort and parenting effort, as indexed by testicular size and nurturing-related brain function, respectively," reads the abstract of the study. In plain English, the researchers at Emory found that fathers with smaller balls were more active in changing, feeding, and caring for their offspring. They also performed brain scans of men of varying testicle size and showed them pictures of children. "It showed those with smaller testicles tended to have a greater response in the reward area of the brain than those with a larger size," the BBC reports.

But let's be honest — it's hard to use testicle size when selecting the father of your children. So while we applaud the brainiacs down in Atlanta, we suggest you also consider the following metrics:

  • A Father That's Okay Not Being the Breadwinner. A study in 1935 from Columbia University found that fathers whose spouses work knew their children better. "One result, according to the study, was that fathers were actually entering into the lives of their children instead of merely supplying money for their rearing,"  the Milwaukee Journal reported (again, remember this is 1935). The catch? Mom (or the other dad) may have less time with kids. 
  • An Older Man. A 1982 study from Kathryn Weil at the University of Nebraska at Lincoln study found that a "recycled father" (a father who first had children at a young age and again became a father between the ages of 46 and 60) and older first-time fathers make better fathers because they're more mature, are in happier marriages, are more willing to share child-care responsibilities and more likely to engage in recreational activities with their kids. The catch? Older fathers are not young. By definition, they are old.
  • A Happy Worker. A study from researchers at Boston University, Charles River Hospital, and McLean Hospital in 1988 found that fathers with happy work lives scored better on key parenting metrics. "Fathers who said they had high job satisfaction tended to show more support for the child's autonomy, which is enjoyment of acting alone, and affiliation, which is enjoyment of relationships with others, than fathers who did not," the AP reported. The catch? Workers are working and thus have less time to spend with kids. Also, they could find a work wife.
  • A Man With a Good Father. Men who had good fathers are more emotionally stable when it comes to stress, a 2010 study from the California State University-Fullerton found. They "found that men who reported having a good relationship with their father during childhood were more likely to be less emotional when reacting to stressful events in their current daily lives than those who had a poor relationship," The Telegraph reported. The catch? Researchers said they needed to research the idea some more. No theory has been developed just yet. Though it does make intuitive sense, no?
  • A Fit Father. This is actually a pretty important metric. In order to get the ball rolling, everyone that's looking to have children should be looking for a man who exercises. Three papers presented during the October meeting of the American Society of Reproductive Medicine in 2011 showed that men who exercised and who ate better were more fertile and had better semen quality—in short, men who take care of themselves have the best chances of making children. The catch? Fit men might have an easier time producing children, but what about raising them? Well, keep in mind that exercise has been shown to further mental well-being, which is important when changing diapers or telling your fifteen-year-old he can't spend his summer vacation surfing in Baja California.

So, for anyone that's looking for father material—you're looking for an older, exercising, man with tiny testicles who is happy at work but is also not working too much, and had a good relationship with his dad.

Or we could all just take our chances.