One of my favourite Nirvana songs is "Serve The Servants". It opens with the splendid lyric "Teenage angst has paid off well, now I’m bored and old" and broods along nicely after that. It's a great tune, but I've always been troubled by the line "I tried hard to have a father, but instead I had a dad."
I believe Kurt has it backwards. He tried hard to have a dad, but instead he had a father. Father is a term that can be applied to anyone who fathers a child. He doesn't need to be anything more than a sperm donor. Fathering a child is easy. A dad is a father who guides their child lovingly through life. Every dad is also a father, but not every father is truly a dad. A dad cares and nurtures his child, and I believe that's what Kurt was looking for.
Trying hard to have a father but instead having a dad doesn't make much sense to me. Kurt got a lot of things right, but he blew a tire on this one.