Talk:Shape-shifter/@comment-139.218.142.222-20140706035158/@comment-7600752-20140706053354

No. The gene doesn't skip a generation. Some members are born with the shape-shifting gene... and others are not. But the gene goes directly in direct lines. It neither parents have the gene - then they can't pass it on. So, one of the parents (usually the father) passes on the gene to the child (usually a boy).

If there are NO vampires in the close immediate area - then the gene remains inactive, or unactivated... the tribe-member remains a normal human. If a vampire comes and stays within a shifter's vicinity - they this will activate the gene and the shifter will begin shifing.

But, you have to be relatively young for this to happen. By the time the Cullen's had come back to Forks, Billy and Harry were too old for the gene to activate. BUT, they stil had the gene because they passed it on to their sons.