Having a kid did that to me, too. I've always been a bit of a crybaby, but now I kinda lose it when children-related kidnappings or deaths happen in movies or TV shows or the news.
Tycho, from Penny Arcade, said it best: "When I was younger, I would have resented some of this stuff - it would have seemed ham-handed. Manipulative. I could have discern what they wanted me to feel and valiantly refused, or (if it were executed especially well) felt a version of it which might have been similar in color or shape. I would feel it in deference to their craft.
That’s not really how it works now. Children carve something out of you, a place for themselves; people can twist the knife in that spot, and it just bleeds and bleeds."