Chris,
I'm sorry you have to battle ignorance in addition to diabetes.  The best
way I have found to handle these types of situations is to become as
knowledgable about your condition.  Then you can enlighten them as to errors
of their thinking.  With diabetes on both sides of your family, and
especially since you have a sister with diabetes, I agree with you that you
have a predisposition to this.
When you tell a friend or family member that you have developed diabetes, I
think that it sometimes scares them.  They in turn start looking for the
"cause," in hopes that they can convince themselves that they "can't" get
it.  If they can find something in you that is different from them, then
they can comfort themselves to some degree.  Only patience, time and
knowledge will solve this.
Good luck, it is always tough to educate the masses.
Steph

How do you deal with the constant stream of supposedly
sympathetic support offered by friends and family when
they learn that you have diabetes, and proceed to lecture
you about how it's your own fault for eating like a pig
for all these years?

I'm 42, 5'9" and 180, and I'm supposed to be losing 39-40 lbs,
but I'm still thinner than most of them. And none of them exercise
at all - they just sit on their couches and watch TV.  I don't go
to the gym, but I am a little bit active: I teach dance several
nights a week, and I also go out and do pretty aerobic dancing
each weekend.  (Of course, now with this condition, I also go
for a walk every day for at least a mile or two.)
It just doesn't seem fair, and I have never once ever
criticized their utterly sedentary lifestyles!

Besides, don't they remember who I was eating all those dinners
with for the last 20 years?

Some of them also insist on giving me bizarre advice, such as not
to drink diet sodas because that is one of the causes of diabetes.

They never raise their voices when criticizing my condition;
they offer it by way of sympathetic explanation.   But I can
hear the deadly accusations in their tone.

I'm a native American on my mother's side, and my father's mother
had diabetes, and my thin sister had diabetes, and so I tend to
think that I have a genetic predisposition for the disease.

But they can't accept that, and just harp on me about what a
fat pig I've been and now I'm getting the consequences.

I wish there were some way to get them to stop.
I feel bad enough already.