What causes stubby tails?

[JodanOrNoDan]

Anybody know what causes stubby tails? I’m assuming it has something to do with incubation because I have two clutch’s, both have babies with short tails and some have stub tails. I’m fearful that my 3rd clutch will also turn out like this. I hope to figure this out before I try incubating any new eggs. I incubated at 89.0 very consistent controlled with a herpstat and had a consistent 99% humidity. I’m clueless to what could of gone wrong. If it was just one clutch or just a couple babies I would of just said bad luck but out of 2 clutches and 17 babies, not one has a normal tail so I’m pretty sure it has to be an incubation problem, I just don’t understand what could of gone wrong. Any help would be appreciated.

I don't think I've never seen this unless it is subtle differences between male female deal. You pop them yet? Pictures please.

BTW, i am incubating at 87 ambient. This is giving me egg temps of 89. I still haven't proved it but I believe the eggs generate heat. The eggs could be hotter than you think.