>>>>PS "in all the years I've been present here" I'm sure you appreciate the English lesson :-)
>>>
>>>Are these the type of mistakes that only non-native writers make?
>>
>>Mostly :) But non-native speakers rarely confuse it's and its as native often do :)
>
>That's true!
>
>Now how about "Ones"? Is it
>
>"I think it's ones duty to help those less fortunate..." or
>
>"I think it's one's duty to help those less fortunate..."?

I would vote for the second, but my English language knowledge is limited.