Is Juggernaut and Sandman Brothers?

Is Juggernaut and Sandman Brothers? 

No, Juggernaut (Cain Marko) and Sandman (Flint Marko) are not brothers.

• Juggernaut is a Marvel Comics character known for his immense strength and durability. His real name is Cain Marko, and he gains his powers from the mystical Crimson Gem of Cyttorak. He is the stepbrother of Professor Charles Xavier (leader of the X-Men).
• Sandman, whose real name is Flint Marko, is a Spider-Man villain with the ability to transform his body into sand. He got his powers after being exposed to radioactive sand in a nuclear testing site.

Although they share a similar last name, there is no family relation between them in the Marvel Universe. Their only connection is that they are both supervillains and have fought against heroes like the X-Men and Spider-Man.