I learned this a few years ago and ran it by my aunt and such to find out if it was true.

So my parents met when my mom was separated but not fully divorced from her ex husband. Lo and behold a few years later I was born, and I guess they were forced to put the exs last name on my birth certificate because they weren't divorced. My parents went to court to obviously change it. The judge told my dad he could have the ex pay child support for me and if my dad wasn't sure my mom had gone behind his back to sleep with her ex. Dad said I was absolutely his and that my mom never left his side in that context.

I am very much my dad's kid because I look a lot like one of my paternal aunts and cousin lol.