My wife lives with her parents and has been for 2 years. The only bill she pays is her car payment. We have one child (6 years). He stays with them about 75% of the time. We own a house and I've been paying the mortgage and all the bills. I also pay for her auto insurance and some things for the kid. My question is should I be paying child support even though she has almost no living expenses and I pay for a house that she owns half of.

Keep all receipts of everything you pay to her or buy for them.
Also many times women that do not feel they NEED the support will accept what you offer rather than go through the court for child support but she just might decide to do it one day.
You should always 'pay' child support because it is your kid, but it is either up to the two of you to decide the how and what or leave it up to the Judge to determine.
My ex never paid child support for my kids and every time I went to child support court they weren't of any help and constantly gave me a run around. I always resented the hurt he caused me and my kids because he couldn't be bothered with making sure they had what they needed. I always felt that the least he could have done was buy their school clothes, Christmas presents and birthday presents. He spent about $10. A piece on Christmas presents for them and it was mostly plastic toys from the dollar store that they were too old for.

My wife lives with her parents and has been for 2 years. The only bill she pays is her car payment. We have one child (6 years). He stays with them about 75% of the time. We own a house and I've been paying the mortgage and all the bills. I also pay for her auto insurance and some things for the kid. My question is should I be paying child support even though she has almost no living expenses and I pay for a house that she owns half of.
I'm not trying to dodge paying for my kid, but his mother has a full time job and lives for free with her parents. The kid gets everything he needs and then some from her, I, and her parents. In fact I get angry sometimes because he gets spoiled too much sometimes over there but I usually keep my mouth shut. If she lived on her own the story would be different and I would pay her weekly to support the kid. I would like to know what a judge might think considering the situation. Does the fact that I'm paying the mortgage for a house that she will be entitled half the equity make a difference while she is living rent free.

I would imagine that if you were to go to court all of this would be taken in to account. Is there no legal separation agreement? 2 years is a long time. From what I have been told anything you have paid to this point is considered a gift if there is no agreement in place. Now, this could vary from state to state. I am in Ohio.
You should be paying something in the form of child support, regarless of what her arrangements are.

Was a support agreement put in place at the time of the divorce? If not, why not? Generally siupport is calculated as a percent of income. What was the disposition of the house in the divorce?