Your comprehension problem is immense. I don't say that to fuck with you, I say it in sincerity.
I've stated that people that can consent, can consent. People that cannot, cannot. The ability to consent isn't something that appears and disappears based on whether you or I like or endorse a given act. It is independent of the act, in most cases.
If a person does not have the wherewithal to consent, they cannot consent. The ability of a person to consent is not fixed at a given age, but generally speaking the older a person becomes the more likely the ability will occur.
If you think different than what I posted above, present your argument as to why my argument is wrong.
In your case if a person does not have the wherewithal to comprehend, they are unable to comprehend. Which is a a nice way of my saying, you're not very bright.