Three...that's the magic number

Can't advise as to the big boy, but I'm a believer in the 4-5 year olds as different creatures theory. Many years back (when my first was just toddling) a friend loaned me a book entitled "Raising Boys" (I think) which had as a premise that boys have three testosterone boosts in their life: birth, puberty, and this 4-5 range.

And yeah, having one go through it and anticipating another reaching it is why I went out and took a parenting course. (My MIL took two to get through this stage!)