Respuesta :
Depends on the year you are asking about.
If you are asking about this year, 2017 :
A person born on October 29th, 1990 will be 27 years old on October 29th, 2017.
If you are asking about this year, 2017 :
A person born on October 29th, 1990 will be 27 years old on October 29th, 2017.