What's the age gap?

I think it's around 19 years?

Blue hair is 27 something and Black haired is 39 something, I think

I don't remember how old the woman (uncle's daughter) is but assuming she's 26 like the main character, the age gap should be like 15 years. Uncle was 23 when his daughter was 8 so he should be around 41 now. Correct me if I'm wrong tho