No tarantula has ever caused a recorded human death. They are gennerally beautiful, viewing pets.
Try a Chilean Rose Hair trantula, one of the easiest, docile, perfect begginer species out there. A 5 gallon (with lid) is fine. They are cheap (from $10-$40) and neat tarantulas. They are good with an unheated source, from 68F-83F is their required temps, and from 72-78 is preferred.
If you keep them resposibly (I.E. not leaving lids off, supervising when children around) you have virtually no need to worry. Even if you handle them while children are around, as long as they are not by faces (because of the urticating hairs) they are ok, and depending on your kids ages, I wouldn't consider surpervised handling a risk, as long as it is relatively tame.
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