Your hair will remain straight up until you wash it.
You can try doing a keratin treatment which makes your hair straight up until it grows out.
Between yuko treatment and keratin my sis likes keratin better. If you do want to try one of those things make sure you do a lot of googling.. and I'm not sure about the cost of it I think its expensive.
You hair is curly because of genetics. No, straightening won't change your genetic make-up. That's like saying that people who dye their hair will lose their natural hair color forever. It doesn't work like that.