Why do some people have lisps? Is there a scientific study or what?

I don't think so. I know someone who was, i guess, born with speech problems and therfore had a bit of a lisp. But I also know people who developed lisps from braces and other orthodontal work. Oh and don't forget about peircings! Alot of people develop them from lip peircings, tongue rings, ect. I must confess I kinda have a thing for lisps LOL. I think their y! Hope this helped. =)