Age group for UX related research

I have a survey which is related to UX and I want to get user demography data from the survey. But I have not much idea about what are the age groups need to consider. In different places, it shows different age groups. As an example, some article says consider age groups like 9 - 19,20 - 34, 35- 50 etc. Some say 25 -34, 35 - 50, 50< . Is there any standard for age groups in UX design? Also, I cannot ask age as a direct number in because it is not much ethical.