What is the meaning of the lisp?

Alright so I am not a myself but this is something I have wondered for a little while now. Why do uals (mostly men from what I notice) speak with that kind of lispy and higher pitched voice? I can't help but think that it isn't intentional. This is because I have an uncle that only just came out of the closet a couple years ago. Up until then he spoke in a typical voice with no kinds of speech alteration but once he came out of the closet and ever since then he has been speaking in a much higher voice and using the lisp. So is it just something that s choose to do or is there a reason behind it? Thanks.