What I know is this. My children come in three versions. I'll use photos to explain.
Version 1 is the deliriously happy child. Typically, this is the child you meet when there's something they want from you. This child should generally be regarded with doubt and the occasional side-eye. This child *sometimes* occurs naturally - typically speaking these natural occurrences fall when 1) they wake you up early in the morning to snuggle just because they love you and 2) late at night when you've allowed them dessert and to stay up past their bedtime.
Here's child version 1:
And listen to me: When version 1 is around and his or her eyes are open, you'll think to yourself "Gosh, what a sweetheart, I'm so glad I had him/her." Or, sometimes you'll think "OMG, I cannot believe I just lost my schmidt with the kid and threatened to send him to the Haitian orphanage we saw on TV." Version #1 can also be found at any point in which the child is sleeping. The smile's not the same, but version #1 while sleeping ALWAYS elicits the "I cannot believe God blessed me with such an amazing and awesome creature when I'm so totally undeserving." while taking a large gulp of beer or tapping a T-box.
But remember, mommies (or soon to be mommies - or wanting to be mommies), every child embodies, like Janus, that second face. That version #2. Version #2 should be handled with aplomb, friends. Version #2 should be met with a raised eyebrow and a "You know, you're only embarrassing yourself." Whatever you do, do not fall into the sad-sack-guile that is Version #2.
What's Version #2? Version #2 is the child that makes old ladies weep for the cruelty you've bestowed upon a stranger to them. Version #2 is the look that makes you think perhaps you should give in just to get him or her to stop looking so pathetic. Trust me, only laughter is the appropriate response to this. Or, perhaps shooting a picture to share with all, and I do mean all, of your friends.
And version #3? Well look, I'd try to explain but nothing, and I do mean nothing, NOTHING can explain version #3 unless or until you've experienced it. It's the shrieking, and I'm not willing to share it, that makes all of the people around you say either 1) "Why can't she control that child" or 2) "A mom so bad as to have children like that shouldn't be a mom." And for those who say that, well let me just say, I cannot wait until you meet your own version #3. It'll be a glorious day - as all the mothers in the world take a deep breath and say "Something has changed in the force."