Some of my childless co-workers resent the fact that our company lets me take time off occasionally to take my kids to the doctor, attend school functions, etc. How do I deal with their resentment?

Sometimes, those without children don't see all the obligations that go with caring for them. They see the doctors' appointments and school functions as undeserved
vacations from work.

You can't control your co-workers' heated reactions, but you can avoid fanning the flames of their responses. For example, avoid calling undue attention to when you are leaving, or will be absent to care for your children. Keep those aware of your absences limited to a need-to-know basis, such as your immediate superiors. If you do have to alert your co-workers, simply say, "I will be late tomorrow," or "I will be leaving early today," without any defensive-sounding explanations for why you must be away from the office.

While it's important to understand you can't affect your co-workers' perceptions on this issue, it's equally important to know you can control your reactions to them. That is, if you perceive their feelings as an attack, you'll go - as your question suggests - on the defensive, which in turn may worsen the overall atmosphere by giving their attitude more significance than it deserves. That's why the best way to handle this conflict is by playing into it as little as possible. As someone said on the TV show, "The Wire," "You cannot lose if you do not play."