I'm still not convinced this has to happen, but as kids get older I noticed language learning isn't as fun as it

She doesn't have fun with learning English, as it is just her mother tongue. She has started English classes at school, but it doesn't challenge her at all yet. She is also learning French and was doing German, but her new school doesn't offer German. She likes learning languages still, which is good - and she has a gift for it.

From the baby's viewpoint it was not Korean but "mom's language" and not English but "Dad's language".

This is how we taught Smallsteps. There was "what daddy says and what mummy says" - her first translation was when she was about 1.5 years old and my wife said something to her, and Smallsteps turned to me and explained what mummy said :D

To this day my second son will blab to his mom in Korean and then turn to me and continue in English without thinking about it.

And this is what my daughter does. It doesn't matter too much for her, but her Finnish vocabulary is stronger.

I don't know how much Fins use English, but I do wish Smallsteps could use both languages fluently.

A lot. This is why it isn't "too much" of an issue, but to be truly mother tongue, she has to keep using it and expanding it. Finns speak English well compared to most of Europe, and Scandinavia in general is very good.

As a teacher of second languages I see students who are free like a child absorb the most and come out speaking fluently.

Are you in Korea yourself?

"Many Blessings in the New Year"

Same to you mate. Hopefully 2026 is a better one overall for the world. I have my reservations though. :)