Type I Diabetes (T1D) is an autoimmune disease where a person's own...

Type I Diabetes (T1D) is an autoimmune disease where a person's own immune system attacks and destroys the insulin-producing cells in their pancreas. Individuals with T1D eventually lose the ability to produce insulin (insulin is required by your body to metabolize sugar). Individuals with T1D must carefully monitor their blood sugar levels and use insulin injections throughout their life.

There are "high-risk" haplotypes associated with T1D. 90-95% of people with T1D have these haplotypes. But of everyone with the haplotypes only ~5% will go on to develop diabetes.

Thinking about a pair of monozygotic* twins, where one has T1D and the other does not, can haplotype differences between the twins could help explain why one developed Type 1 Diabetes and one did not? Explain your answer.