Could having a gap between your teeth cause a lisp?

See a dentist: It's possible. It's best to have your gap evaluated by a dentist and also evaluate your tongue, because it plays a major role in speech.

Not usually: Most lisps involve lack of total tongue movement, either from the lingual frenum( tongue tied) or constricted movement from teeth constricting movement.

Probably not: Small gaps of just a few millimeters are not enough to alter speech. A narrow palate, a large horizontal overbite, multiple missing teeth, neuromuscular pattern, can all cause lisp. See 1) dentist or orthodontist to evaluate occlusion, and 2) speech therapist to evaluate tongue fundtion.