Baby box turtles of 3 years old have not grown

We have had baby box turtles growing for 3 years now and they do not seem to be growing. Like the same size 2 years ago as they are now. They have correct lighting, heat, food and supplements. Could it be genetic? The babies were from captive bred and raised box turtles frok different parents so there was no inbreeding. Any ideas? I am not the breeder so I don't know much but could it be due to them living so long they grow slow or...?

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How big are they now?

Originally Posted by elena

How big are they now?

We have two runts (2 1/2 inches) and the rest are 4-5 inches

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Box turtles are very competitive for food. Try separating the smaller ones. I would also try and get them outside as much as possible. It's easy to construct some thing outside that gives shade and sun.