How could Josiahs 4th son have been born when his father was 16?

How could Josiahs 4th son have been born when his father was 16?

Jehoahaz (called Shallum), fourth in the list of Josiahs sons (1 Chronicles 3:15), was 23 when he began his 3 month reign (2 Kings 23:31). His father had reigned 31 years (22:1), So Jehoahaz was born in the eighth year of his fathers reign, when his father was about 16. At 25, Jehoiakim succeeded Jehoahaz three months (2 Chronicles 36:2) after his father died. Allowing for differences in birthdays, Josiah must have been 15, at most, when Jehoiakim his second son was born.

2 Kings 24:18 shows that Zechariah was 13 years younger than Jehoahaz. So Jehoahaz was the third son, not the fourth. Since Jehoahaz and Jehoiachim had different mothers (2 Kings 23:31, 36) and Johanan may have had a different mother, Josiah may have been, at most, 15 when his first son was born. This is still very young, but may be easier to understand.

D. Oliver