That all seems pretty simple, but it’s far less cut-and-dry when you try to explain those facts to a child, who is just learning what gender even means. So instead of talking about whether someone is transgender or not, and whether they are a boy or girl, try talking about who they are on the outside, compared to how they feel on the inside and compared to who they were when they were born. When kids are young (think elementary school age) start simple, and focus on the fact that sometimes people are born in one body, but in their hearts they know that they really feel like someone different. You can keep it very basic; your kids will listen and they will understand you.