I think it is both, being new and being young. I've joined the local quilt guild almost 4 years ago. I've been attending the Wednesday meeting since then, attended workshops, made several charity quilts and even brought a new member. Well, last Saturday I am in a charity workshop and somebody approached me. She said that the quilt guild is starting a new "thing" which is to introduce the young new members and here she is asking me questions to present me on the next meeting. At the end of the questionnaire I told her.... I've been in this guild for 4 years, I am not new... but bottom line the initiative is good. I guess that each group needs to come to the conclusion that they need to accept and welcome new members young or not so much.
Don't quit, they are usually closed groups and eventually the will accept you. In my guild they accept you faster if you belong to a Bee which I don't.
good luck.
andrea