Psychologists have long studied the phenomenon of team spirit. Why is that we as fans feel so strongly about our teams? What makes us stay loyal to one team even as we move across the country? What makes us want to pass that love on to our children?

One reason is the parents’ memories of the enjoyment that they derived watching a certain team. If enough of that enjoyment is compounded over the years in the form of happy memories, a legacy of sorts is fashioned. No matter how well they do in the current NBA season, for example, Bulls baby clothes always sell really well.

Why are Bulls baby clothes such hot sellers? Part of the reason for this is the average age of parents and friends doing the purchasing.

Over the last few years, teenage pregnancy rates in America have dropped, reaching a 30 year low in 2008. The average parent is now most likely to be between 25-29 years old. People who fall within this age demographic still remember seeing the amazing play and championship domination of the Bulls’ glory days in the mid-90s, when players like Michael Jordan and Scottie Pippen defined the Bulls’ brand and created professional hoops fans worldwide.

Other parents – and the purchases that they make – are truly tied to the physical location from which the team hails. No fan base is more demonstrative than the Steeler Nation, the passionate legion of Pittsburgh Steeler fans.

Many economic experts attribute the nationwide nature of this passion for Pittsburgh pro football to an economic source; namely, the decline of the steel industry in Pittsburgh, which forced many of the city’s natives to leave home and relocate all over the United States in order to find work. For Steeler fans, passing the love of the team on to future generations is a no-brainer – even if those fans have been forced by circumstance to leave that city with those three famous rivers.

Another reason that parents pass their fanhood to children: the values the team represents.

In a time where most teams are corporately owned and have a roster of super rich athletes, the Green Bay Packers remain the only community owned, non-profit sports team in the country. Due to an ownership policy enacted in the 1980s, there will never be another NFL team owned by shareholders who are actually fans of the team.

Perhaps because of this ownership structure, the Packers have stayed in the same location, with the same name, for over 100 years. Players have been known to hold Bible study together and meet young fans outside training camp in the summer, honoring a tradition that began 50 years ago. For Packer fans, draping your baby in green and yellow is to teach the child about tradition and loyalty.