Albert Einstein was widely regarded as a genius because of his groundbreaking contributions to physics, such as the theory of relativity, the energy-mass equation, and the photoelectric effect. He was also the recipient of the Novel Prize in Physics in 1921 for his work on the photoelectric effect.
Some studies have suggested that Einstein's brain had some unusual features that may have been related to his extraordinary cognitive abilities, such as a higher density of neurons, a higher ratio of glia to neurons, and a different pattern of grooves and ridges in some parts of the brain.
Einstein's genius may have been influenced by a combination of factors, such as his innate curiosity, his imagination, his persistence, his education, and his environment. He was also known for his humanitarian and pacifist views and his involvement in social and political causes.
Therefore Einstein was a genius not only because of his remarkable scientific achievements, but also because of his personality, his values, and his impact on the world.