citizenship n tax return

[haf]

Hi
I will apply for citizenship this year with me n my parents we willbe 5 yrs.but my mom is 62 and dad is 67 since they came here they never work that much so i usually show them my dependents and never file their tax seperate .but this year people were saying to file thier seperate too i want to knw will it affect citizenship or if i couldn't able to file their separate what will happen??whats its impact
Kindly need better advice.if rajiv can help too
Really appreciated
Thanx

 

[Jackolantern]

Did they have income since obtaining their green cards?

 

[haf]

Not continuous income since we get green card there is no income.i support them with my uncle.