If the leader is in his or her 40's or 50's, then most of the team is in their 40's or 50's. If the leader is in his or her 20's, then most of the team is in their 20's.
If you are not intentional about bringing age diversity to your team, that is what happens. The natural bent is to attract and hire people who are in the same season of life as you.
The limitations to this? If everyone is young, then you have the energy and new ideas of youth that's not balanced with the wisdom of experience. The flip side...if everyone is middle-aged or older, then you have the wisdom of experience that's not balanced with the energy and new ideas of youth.
A great team has the energy and new ideas of youth coupled with the wisdom of experience.
The older you get, the more intentional you must be to gather young leaders around you. They will keep you connected to current culture and bring energy, new ideas, creativity, and dreams.
If you're a team of young leaders, be intentional about gathering some leaders around you that have experience and wisdom. They can help you navigate decisions and plans and help you avoid the mistakes they made when they were your age.
Take a look at your team. All gray hair? Time to bring in some people wearing skinny jeans. All skinny jeans? Time to bring in some gray hair.
In other words...bring some balance and you'll see your team go to the next level.