Consistency Check:Birth date of Hezekiah Tinkham and his brother Helkiah Tinkham, Jr. are within 8 months.
They are twins. Did you look at the About of their father? That's where you will often find the list of children with birthdates.
I fixed the birthdate that was August 5, missing the "1" to August 15, but otherwise the clues were all there -- in the About of the father and in the fact that their birthdates were nearly identical.