Yes, it is OK to not have children. If it were not, that would imply that every woman in the history of the world who did not produce a child was somehow less than a woman. What about Mother Teresa? Did she ever have a child? Yet, she was a positive influence in the lives of so many children.
The world is full of children that are unwanted. Why on earth should anyone feel guilty about not adding to those numbers? In fact, I would like to see more people adopting the millions of children across the globe that are starving, abused, ill cared for and living from hand to mouth now.
The very idea of having a child to carry on a family name is problematic at best. Suppose one buys into it and pumps out 10 kids. If they are all girls, chances are the family name is toast in one generation anyway. As for the genes, considering we all came from someone, chances are they are already out there in abundance in the gene pool.
Don’t let the narrow minded beliefs of those who never stopped to question them anyway make you feel guilty. It’s your life. Live it how you want. When it’s over, the only person you will be answering to is yourself and God.