Dads, have you ever demanded a paternity test? Why?

I'm not a Dad. But my husband did request a paternity test for his oldest daughter. He didn't believe by what appeared to be the timeline for conception that he could be the father. We requested a test from the local child support office and they had a fit. (The possible father cannot do such a thing) In our state legally he can. We had to go above the heads to get the paperwork. We filled it out and brought it in. The local workers still had a fit. "How did you get these papers? Where did they come from?" I will be honest it kind of gave us some joy when we told them "From your boss, Mr. Whatever" Their whole attitude changed but you tell they were mad but had no choice. They started going on about if the results were positive he would have to pay child support and back child support. 
Finally got results and he is the Father. He of course paid child support but thankfully didn't have to fight over back child support the Mother did not seek it. 

Yes. How did my twin girls come to be like this?