Board Thread:Manga/@comment-27713352-20160909233230/@comment-27321453-20160912044853

Grisha is married at 20

Zeke is born 10 months later (Grisha is 21)

The family pose for the photograph 3 years later (Grisha is 24, Zeke is 3 years old)

Grisha is found outside the Walls 5 years later (Grisha 29, Zeke is 8 years old)

Grisha allows Eren to devour him 15 years later (Grisha is 44, Zeke is 23 years old)

Grisha been dead for 5 years by the time Zeke climbs the Walls (Zeke is 28 years old)

5-6 months later (by the time of the recent battle) Zeke is nearly 29 years old. And that's how Zeke can be Eren's half brother, lol.