I’ve posted several articles here recently showing that gene manipulation done by humans isn’t always done by splicing, surely you’re aware?
Since my PhD major was Biochemistry and Molecular Biology, and molecular biology is the study of nucleic acids and their manipulation, I think that I'm actually more aware than the average person of how various forms of genetic manipulation are performed. Any of them are going to leave telltale signs, even if they are not achieved by the old method of using restriction endonucleases and ligases to cut and splice the nucleic acids.