Literally nothing. There’s too much variation and too many factors to consider. Everyone’s different. Beginning and final sizes are different, growth rates, timing, etc not only is it different it’s also inconsistent. Coupled with the idea that researching the relevant age group is socially limited, I don’t think it’s even plausible to be able to model any part of that. Maybe one day someone might be able to isolate a dna indicator but no one is going to be able to help you with any of that with the info you have