Languages
If we class mother tongue as the first language you learn and are exposed to..... then mine would be italian although by the time i started school my mother decided that it would be better for me to be spoken to in english so i didn't feel out of place or suffer any disadvantages....
Things evolved to the point where i've spoken to my family in english and they speak to me in italian, which other people find confusing

Works for us

Thanks to the efforts of my mother..... my english language skills were never compromised by having foreign parents

I did my first degree in arabic..... and given that i've not used it for years means that my spoken arabic is pretty awful, and i'd learnt egyptian arabic for conversation purposes and got confused when travelling around other parts of the Arab world. Being able to use french when i couldn't find the words in arabic meant that i now start sentences in arabic and finish them in french

But i can still read and write arabic and i don't think i'll ever forget that skill

My french isn't too bad.... helped by my italian..... but ruined by my arabic
So yes..... i am a polyglot..... but i tend to speak all the languages at the same time

which makes my knowing any of them more or less redundant