How did they grow up? Do they have any SN?
Seems like an odd thing to ask but I've seen some research that links babies getting all their teeth before their first birthday and autism. I have a 7 month old with nearly 8 teeth (since the new year), an older child awaiting ASD assessment and a brother with ASD so it's a bit close to home.
Also regardless of SN, did their baby teeth fall out quickly again? How is their dental health?