D N A shocked me

I had a very eventful sex life while at university and after I met and married my late wife and had 3 children before she passed away from cancer 2 years ago. I was left to raise our children alone, which I enjoy a great deal. Late 2019 then 46 I was contacted by my brother Mark about him having a D N A test to discover our family history. He was curious of where our forefathers came from, but that's not the reason her called, after having the test he was contact by the testers that there was match with woman looking for her father. The woman Julia now 22 was raise by her mother Karen alone, Karen had passed away in an accident a year or so before and Julia decided to track down her father as Karen hadn't ever told her anything about him. The testers said that Mark was a close match to Julia, but not the father most likely a sibling of the father. I'm George only male sibling of Mark hence the phone call. I was shocked at first and thought it was some sort of weird joke. I hadn't gotten any woman pregnant while at the university. Karen been at the university the same time as me, but I didn't recall her name straight away. So I done what I could and went thru pictures in year books and found Karen photo and I remembered her face. But wasn't sure if we were lovers, Mark wanted to know if I would willing to meet Julia. I wasn't sure at first but finally decided I should. But first the testers wanted to do a D N A test on me just incase. I was a perfect match for her father, then a meeting was arranged. Luckily I didn't have to go far as Julia was at the same university as I and her late mother had been and I still lived in the area. So we met and by then I had remembered sleeping Karen and then she broke the relationship suddenly. Julia had found an old diary of her mother saying she had slept with a man to get pregnant and to have a baby and raise the child by herself and wasn't going to tell the man about the child. Karen wanted a child and didn't want to marry anyone and when she got pregnant she kept quiet and raised Julia alone. I liked Julia and we started to get to know each other, I introduce her to my 3 children and they liked her a lot like me. With Julia alone with out close family and the coronavirus pandemic I had her move with us and we have since become one family.