This question clearly shows creationists' ignorance. Yet, because I can't answer this question when I have conversations with creationists, they think that they won and that they have me stumped, and therefore evolution can't be true. But, this would be exactly like asking, "if we came from adults, why are there still adults?" This question is always brought up by creationists maybe as a last resort argument or something but its so annoying.
Also, I hate when people refer to evolution as "just a theory, so it hasn't been proved true yet." I dont have good responses to this one either but this frustrates me. I know evolution is true but creationists get on my nerves when they bring up these two arguments.