I think most of us hope for a mixed family and the same with grandchildren.
I have counted my blessings as a grandmother ever since DGD's birth. When DGD was a few months old I accompanied DDiL, with DGD, when she went to view the house they now own. We were shown round by the female householder,she had been a nursery nurse and worked with little children all her life, but told us, towards the end of the viewing, with visible emotion, that both her DSs and wives had decided not to have children.
My sympathies were all with her, DS and wife had married quite late and wanted children but we knew that, at nearly 40, DDiL's chances of conceiving were reducing almost by the day, so the possibility of not being a grandparent had been faced and dealt with. The arrival of DGD and, later, her little brother, have always been seen as wonderful blessing and bonus.