whats theirs is theirs and whats mine is well...theres

ok heres the thing. My mom and dad they are broke. And me well i have some money not much but well more then them. And i feel that it is my duty to help them if i can seeing that they gave me life an all. but when do ya say enough is enough? When do you say I work hard for my thing things so please let me keep them? When you say that i have had enough? How can i say it with out sounding like a spoilld brat? When do i say it my life?