That's weird. I find people with kids care more about personal and professional development, and are more diligent in their work.

This might have to do with the environment I'm in (7,5 hour days with almost no overtime; recruiting motivated people).

I also personally feel I've become more responsible in all areas of my life after having kids.

Edit: I'm mid thirties too. I find the least responsible people to be those in their 50s with no kids. But I've only met a few who remained developers; most either have kids or switched to management.