Can I use gerunds with the word "concede" without using preposition "to" as in the sentence below?
He concedes killing his wife.
Actually, it appears that no one says any of those, perhaps because concede does not work that way:
On the other hand, if you swap admits in for concedes, now you get a more interesting picture:
And here is the past-tense version of the same:
I find especially curious that this only started getting said come the 20th century. That part I don’t know what to make of.
In any event, it appears that admitting doing anything is fairly new to the English language, and following that admit with a to before an -ing form is a very recent phenomenon indeed.