Religion - I don't buy it. I never have, even from a young age. The idea of a mystical all powerful being floating in the sky watching us has always seemed absurd. And frankly, science has really done a number on my ability to believe in traditional religions. Do I believe some higher-being may exist? Sure. Do I believe in an afterlife? No, I don't think anything points to that existing. Maybe it does, but likely it doesn't. But trust me I understand how this lack of a philosophy for life has sucked a lot of community, and to some extent, love for life itself, right out of it.
Children - If there is no afterlife, then what IS the point of this life? Seriously? Why form bonds, and relationships, and become close with people... if only to die and for it all to vanish? Of course since I'm alive, I take every chance to form relationships and bonds. But I don't believe in continuing this depressing cycle. I don't believe in this "system" of pulling someone into the world, only for them to have to say goodbye to everything they've built and everyone they love. I disagree with it at the core of my being, and I've never had a "religion" to help me think otherwise.
So yea... having kids, settling down, religion... that's all gone for me.