I am ashamed to say that also one possible reason why young people are not seen in sessions with older people is older peoples behaviour 2 examples from a festival I have just returned from.
A group of 4 people young with instruments are in a fringe pub at this festival sat at a table talking apart from them the room is empty a gentleman comes in with Instruments followed by his mate they have an animated conversation at the bar with the landlord, the landlord comes over asks the young people to move because they are sat where these 2 always sit.
A family are sat in another pub with a child unaware that there is a session about to start, they are talking a musician places a chair (for no good reason that I can see apart from being confrontational) as close as possible to these people so that they are hemmed in they are then told to stop talking no one explained to this family what was going on no one was pleasant to them, the vast majority of people in this room where OLD.
I have seen this and feel ashamed, this is how OLD people behave I am pleased that young people like and consider me part of their group and allow me to participate with them