2 years old now in 2023 - what year born?

Today, 24 September 2023 if a person is 2 years old now, what year was he born? See below:

If 2 years old, year of birth is:
2020 or 2021*

*It depends on whether he was born before or after 1 January 2021.

If now 2 years and his year of birth 2020 if he was born after 24 September 2020 until 31 december 2020 inclusively, and his year of birth is 2021 if he was born from 1 January 2021 to 24 September 2021.

Other examples:

If now 6 years, year of birth 2016 or 2017
If now 17 years, year of birth 2005 or 2006
If now 29 years, year of birth 1993 or 1994
If now 77 years, year of birth 1945 or 1946

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