Why is there a stigma [bad feelings or disdain] attached to sex/sexuality?

[KAy Kay]

Yes, sex is demonized and
people act like it's something
dirty or shameful.

 

[PeachPie]

Christians and prudes demonized it.

 

[rebekkah]

Probably all those years of church domination and inquisition. We need to move on.