35 years old now in 2021 - what year born?

Today, 16 September 2021 if a person is 35 years old now, what year was he born? See below:

If 35 years old, year of birth is:
1985 or 1986*

*It depends on whether he was born before or after 1 January 1986.

If now 35 years and his year of birth 1985 if he was born after 16 September 1985 until 31 december 1985 inclusively, and his year of birth is 1986 if he was born from 1 January 1986 to 16 September 1986.

Other examples:

If now 10 years, year of birth 2010 or 2011
If now 13 years, year of birth 2007 or 2008
If now 28 years, year of birth 1992 or 1993
If now 67 years, year of birth 1953 or 1954

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