I am reading Hypothyroidism: The Unsuspected Illness written back in 1976 and the author Dr Barnes talks about treating children and gives several examples. Like goolarra said, it does run in families and best to have your daughter tested. Good luck!
Thyroid disease doesn't discriminate by age. While older people are often the ones who develop it, children are not immune. Thyroid disease tends to "run in families", which is a term used when a genetic connection is suspected, but unproven.
Have your daughter's FREE T3, FREE T4 and TSH tested to see where her thyroid hormones are at. You might also want to have thyroid antibodies, TSI (thyroid stimulating immunoglobulin) tested to see if she has Graves'.