> DNA sequencing and analysis of duplicated mice revealed no differences between early and later generations of clones. But that began to change after generation 27, when genetic abnormalities began to negatively affect fertility.
If there were "no differences" between early and later generations of clones, then what "abnormalities" are they talking about?
The suggestion then is that other information about the iteration of copies of copies is being passed, from the article:
There may have been several causes behind the abnormalities that arose in later generations.
{various potential causes discussed}
If the Popular Mechanics paraphrasing of the original paper is poor, there's always the OG source:Limitations of serial cloning in mammals - https://www.nature.com/articles/s41467-026-69765-7