<<Disclaimer: Verify this information before applying it to your situation.>>

Many responded that both twins have celiac, and of course some don't.

"There have been studies done on this. There is a 70% concordance
between identical twins. That is, if one twin is celiac there is a 70%
chance that the other will be also. That's how we know that CD is
primarily hereditary, but also involves an environmental trigger"

Lila - ND