Parents charged with Truancy for 18 yo

What is the name of your state? Texas

We received a court order to appear for truancy for our 18 yo daughter. Isn't she considered an adult? Can they charge us and her with this?

Yep you can be charged. Because you were. Why wasn't your daughter in school? When did she turn 18? When was the truancy committed? Before or after her birthday? More information would be nice.