Alma 3:18-19
I am not sure there is anything to say than what is said here in the scripture. The Amlicites were unaware that they were fulfilling the word of the Lord by marking themselves, but aware or not, they had met the conditions to have the curse fall upon them because they had come out in open rebellion against the people of God. Like the Amlicites, anyone who is cursed, brings their own curses upon themselves and by their own works, they bring their own condemnation. None are condemned by the sins of another.