My mother, father, Grandma, Grandpa, Aunts & Uncles, never had thyroid disease, but my sister and I both have thyroid cnditions, both of us have enlarged thryoid, I was diagnosed hyper today, my sister is borderline hyper.
My mom is type II diabetic, and no one else in our familiy is diabetic. She is the only one.
So according to my family, one person cannot pass on a health condition to another.
It is herditary, but not necessarily so... my grandmother had graves and gave it to one of her two children...my mom and my mom gave it to one of her three children...me. So both of your children could live graves free, think positive!