Board Thread:General Discussion/@comment-4913740-20130707123202/@comment-4913740-20130707152907

He may have exploded in MGS3, but there is no guarantee that his DNA wasn't retrieved prior to this and possibly the first attempt at cloning.

However, I think it's heavily implied that LET was the very first successful cloning attempt. For Quiet to look the age she does (around her 20s), she would've needed to be "born" in 1964. So it's highly unlikely they even perfected the cloning process anyway.