Francis Galton said 1/2 of our genetic makeup is derived from each parent and 1/4 from each grandparent, and 1/8 from each great-parent and so forth.
Yes, it is right. We receive half of our genetic makeup from each parent.
Each parent derives half of their genetic makeup from each of their parents (that means, we derive 1/4 from each of our grandparents).
Our grandparents derived half of their genetic makeup from each of their parents (so, we derive 1/8 from each of our great-grandparents). So, what Francis Galton told was correct.