[Tax-chick]

She is convinced that he duped her mother, Valerie Fleming, into wrongly naming him on the birth certificate as Donna’s biological father

Valerie didn't know who her child's father really was?

[vimto]

Hey you want to live in some places around here - it's common. The problems associated with multiple sexual partners is causing serious concern not least with possible incest of future couplings of half brothers and sisters who have no idea they are related. (but no-one will say so because of PC). I know this as a fact from my time a vicar with the Marriage regulations.

"If the good Lord wanted me to remember the father he wouldn't get me so drunk on a Friday night" or something like that.

Having said that I doubt this refers to such a situation.