We belong to the unfortunate club of multi-generational diabetes families. My wife's maternal grandfather was diagnosed with Type 1 the year insulin was "discovered." Her dad has it, her brother, and our daughter. Two years ago my wife was diagnosed with type-1 diabetes at the age of 42. Go figure.
She was wracked with guilt about passing this on to our child, but her dad had the best insight: No one asked for their genes. You get what you're dealt and you have no control over passing it on to your kids.
But what we DO, every day to manage blood sugars IS under our control. As long as we do what we can, there's no space for guilt.