"You can't be asexual.  You can't clone yourself."- Although the term 'asexual' is used in the biological sciences to indicate an organism that can reproduce by itself, whether by cloning or by splitting in two, it has different meaning when applied to human beings.  It can very hurtful for asexual people to hear themselves compared to microorganisms.

 

"So you don't want anyone to have sex ever?"- Like sexuals, asexuals have varying degrees of sex-positivity.  Many asexuals believe that sex is a positive thing when between consenting adults, and that people should be able to express their sexuality as they choose.  This includes the freedom to not have sex.

 

"You must have been traumatized as a child."- Asexuals are no more or less likely to have suffered sexual abuse or trauma than sexuals.  Asexuality is not the result of a traumatic childhood; it is a legitimate sexual orientation.  Although the causes of asexuality, like the causes of any other sexuality remain unknown, it is unlikely that childhood abuse can cause a change in sexuality.

 

"How do you know if you're really asexual? You've never had sex."- Asexuals are faced with a catch-22: if you have had sex, people say, you can't be asexual, and if you haven't had sex then you can't know you're an asexual.  A straight person doesn't need to have sex with a person of the same gender to know that they are straight!  And a pansexual person doesn't need to have sex with someone of "every" gender (hardly possible) to identify as pansexual.  Moreover, statements like these contribute to coercive pressures on asexual people to have sex without desiring it and help perpetuate rape culture.  Respect people's identities; only they know their experiences.