It is a fact that people have proposed that aliens make crop circles, but that says nothing about the truth of "aliens make crop circles".
That Wikipedia text quote is full of the former kind of phrase, using "Possible causes have been identified", "other proposed causes", and "other possibilities".
The sentence you emphasized starts with such a phrase:
"other possibilities have included […] genetically modified (GM) crops with pest control characteristics"
And then further weakens the statement with "although no evidence has been found to suggest this.*"
So, if I read that Wikipedia article, I mostly read "we don't know."
That Wikipedia text quote is full of the former kind of phrase, using "Possible causes have been identified", "other proposed causes", and "other possibilities".
The sentence you emphasized starts with such a phrase:
"other possibilities have included […] genetically modified (GM) crops with pest control characteristics"
And then further weakens the statement with "although no evidence has been found to suggest this.*"
So, if I read that Wikipedia article, I mostly read "we don't know."