Board Thread:General Discussion/@comment-7526254-20150520160921/@comment-25926288-20180423083720

Adam said that Hamilton debuted 18 months earlier, which means early 2014.

As for Henry, you don’t have to be pregnant for 9 months to have a child. Sometimes they are pre-mature. So, likely that was the case for Henry. (I’m sure the writers just aren’t too keen on math.)