My kids and I have NF1 also. We just got dxed with it.
My daughter does--son doesn't. I think my mother and at least one of her brothers did. He had 1 leg a little shorter than the other and lots of "back problems" (scoliosis?) Mother had some "bumps." Mother would be 95 and her brother was older than her so no diagnosis for either of them. My gene may be a "mutation" but I think not--but can't prove either way!