Yes, that would be okay, though the other clan leaders won't take him/her as seriously. Any genin could be specifically under one of the clan heads as a pupil, or under someone who can offer them training and protection. I figure if you're playing a genin, you're doing it for the long term character development more than you would be doing it for combat.

So I mean I'd suggest people keep to Chuunin and above. Later on genin will become more accessible. After all, this is a generational RP, it's just [I]getting[/I] to that point may take a bit.