that's the odd thing with me and my brother... I hold my knife in my left hand and fork in the right, but my brother is right handed and holds his knife and fork the opposite way. I don't know what the 'proper' way is supposed to be.
FWIW it dates from before cutlery. You kept your dagger or shortsword in your right hand and used that for cutting meat, skewering food you couldn't reach etc and it meant that you had it handy if a fight broke out.
But I'm with your brother I always use the fork in my right hand - and I'm right handed.